INVESTMENT AND OTHER SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Available-for-sale securities:
Less than 12 Months, Fair Value	$ 12,866	$ 1,198
Less than 12 Months, Gross Unrealized Losses	(96)	(14)
Over 12 Months, Fair Value	15,357	16,499
Over 12 Months, Gross Unrealized Losses	(2,502)	(2,430)
Total, Fair Value	28,223	17,697
Total, Gross Unrealized Losses	(2,598)	(2,444)
Held-to-maturity securities:
Less than 12 Months, Fair Value	1,536	48
Less than 12 Months, Gross Unrealized Losses	(10)	0
Over 12 Months, Fair Value	10,111	11,079
Over 12 Months, Gross Unrealized Losses	(1,699)	(1,647)
Total held-to-maturity securities	11,647	11,127
Total, Gross Unrealized Losses	(1,709)	(1,647)
U.S. Treasury
Available-for-sale securities:
Less than 12 Months, Fair Value	5,724	0
Less than 12 Months, Gross Unrealized Losses	(25)	0
Over 12 Months, Fair Value	0	439
Over 12 Months, Gross Unrealized Losses	0	0
Total, Fair Value	5,724	439
Total, Gross Unrealized Losses	(25)	0
Held-to-maturity securities:
Less than 12 Months, Fair Value	1,230	0
Less than 12 Months, Gross Unrealized Losses	(8)	0
Over 12 Months, Fair Value	0	289
Over 12 Months, Gross Unrealized Losses	0	0
Total held-to-maturity securities	1,230	289
Total, Gross Unrealized Losses	(8)	0
Total U.S. Treasury, federal agency, and other agency securities
Available-for-sale securities:
Less than 12 Months, Fair Value	11,430	144
Less than 12 Months, Gross Unrealized Losses	(74)	0
Over 12 Months, Fair Value	12,820	14,145
Over 12 Months, Gross Unrealized Losses	(2,385)	(2,333)
Total, Fair Value	24,250	14,289
Total, Gross Unrealized Losses	(2,459)	(2,333)
Held-to-maturity securities:
Less than 12 Months, Fair Value	1,536	48
Less than 12 Months, Gross Unrealized Losses	(10)	0
Over 12 Months, Fair Value	10,110	11,078
Over 12 Months, Gross Unrealized Losses	(1,699)	(1,647)
Total held-to-maturity securities	11,646	11,126
Total, Gross Unrealized Losses	(1,709)	(1,647)
Residential MBS
Available-for-sale securities:
Less than 12 Months, Fair Value	2,945	55
Less than 12 Months, Gross Unrealized Losses	(34)	0
Over 12 Months, Fair Value	8,645	9,185
Over 12 Months, Gross Unrealized Losses	(1,391)	(1,365)
Total, Fair Value	11,590	9,240
Total, Gross Unrealized Losses	(1,425)	(1,365)
Held-to-maturity securities:
Less than 12 Months, Fair Value	73	0
Less than 12 Months, Gross Unrealized Losses	(1)	0
Over 12 Months, Fair Value	6,282	6,694
Over 12 Months, Gross Unrealized Losses	(963)	(941)
Total held-to-maturity securities	6,355	6,694
Total, Gross Unrealized Losses	(964)	(941)
Residential CMO
Available-for-sale securities:
Less than 12 Months, Fair Value	1,754	51
Less than 12 Months, Gross Unrealized Losses	(9)	0
Over 12 Months, Fair Value	2,335	2,665
Over 12 Months, Gross Unrealized Losses	(331)	(308)
Total, Fair Value	4,089	2,716
Total, Gross Unrealized Losses	(340)	(308)
Held-to-maturity securities:
Less than 12 Months, Fair Value	233	48
Less than 12 Months, Gross Unrealized Losses	(1)	0
Over 12 Months, Fair Value	2,765	2,956
Over 12 Months, Gross Unrealized Losses	(547)	(520)
Total held-to-maturity securities	2,998	3,004
Total, Gross Unrealized Losses	(548)	(520)
Commercial MBS
Available-for-sale securities:
Less than 12 Months, Fair Value	637	23
Less than 12 Months, Gross Unrealized Losses	(5)	0
Over 12 Months, Fair Value	1,767	1,782
Over 12 Months, Gross Unrealized Losses	(661)	(657)
Total, Fair Value	2,404	1,805
Total, Gross Unrealized Losses	(666)	(657)
Held-to-maturity securities:
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Gross Unrealized Losses	0	0
Over 12 Months, Fair Value	1,027	1,094
Over 12 Months, Gross Unrealized Losses	(187)	(184)
Total held-to-maturity securities	1,027	1,094
Total, Gross Unrealized Losses	(187)	(184)
Other agencies
Available-for-sale securities:
Less than 12 Months, Fair Value	370	15
Less than 12 Months, Gross Unrealized Losses	(1)	0
Over 12 Months, Fair Value	73	74
Over 12 Months, Gross Unrealized Losses	(2)	(3)
Total, Fair Value	443	89
Total, Gross Unrealized Losses	(3)	(3)
Held-to-maturity securities:
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Gross Unrealized Losses	0	0
Over 12 Months, Fair Value	36	45
Over 12 Months, Gross Unrealized Losses	(2)	(2)
Total held-to-maturity securities	36	45
Total, Gross Unrealized Losses	(2)	(2)
Municipal securities
Available-for-sale securities:
Less than 12 Months, Fair Value	1,433	1,043
Less than 12 Months, Gross Unrealized Losses	(22)	(14)
Over 12 Months, Fair Value	2,122	1,892
Over 12 Months, Gross Unrealized Losses	(86)	(67)
Total, Fair Value	3,555	2,935
Total, Gross Unrealized Losses	(108)	(81)
Held-to-maturity securities:
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Gross Unrealized Losses	0	0
Over 12 Months, Fair Value	1	1
Over 12 Months, Gross Unrealized Losses	0	0
Total held-to-maturity securities	1	1
Total, Gross Unrealized Losses	0	0
Corporate debt
Available-for-sale securities:
Less than 12 Months, Fair Value	0	2
Less than 12 Months, Gross Unrealized Losses	0	0
Over 12 Months, Fair Value	169	176
Over 12 Months, Gross Unrealized Losses	(17)	(15)
Total, Fair Value	169	178
Total, Gross Unrealized Losses	(17)	(15)
Asset-backed securities
Available-for-sale securities:
Less than 12 Months, Fair Value	0	9
Less than 12 Months, Gross Unrealized Losses	0	0
Over 12 Months, Fair Value	176	207
Over 12 Months, Gross Unrealized Losses	(7)	(8)
Total, Fair Value	176	216
Total, Gross Unrealized Losses	(7)	(8)
Private-label CMO
Available-for-sale securities:
Less than 12 Months, Fair Value	3	0
Less than 12 Months, Gross Unrealized Losses	0	0
Over 12 Months, Fair Value	70	79
Over 12 Months, Gross Unrealized Losses	(7)	(7)
Total, Fair Value	73	79
Total, Gross Unrealized Losses	$ (7)	$ (7)

No definition available.

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479081/326-30-55-8

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-7

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479081/326-30-55-8

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesClassifiedAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-7

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-6

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

+ References

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

+ References

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-7

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-6

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months.

+ References

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.

+ References

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=hban_OtherFederalAgenciesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: