Commitments and contingencies.

No definition available.

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- Definition

Expected spend amount remaining for construction.

+ References

No definition available.

+ Details

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Namespace Prefix:	carg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Guarantee income.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Guarantor Obligation Term Description

+ References

No definition available.

+ Details

Name:	carg_GuarantorObligationTermDescription
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Balance Type:	na
Period Type:	duration

- Definition

Increase (decrease) in tenant improvement allowance.

+ References

No definition available.

+ Details

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Namespace Prefix:	carg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of days guarantee period.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Operating lease, decrease in right-of-use asset due to re-measurement from lease amendment.

+ References

No definition available.

+ Details

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Namespace Prefix:	carg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Area of land held.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Amount of contractual obligation, including, but not limited to, long-term debt, lease obligation, purchase obligation, and other commitments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3

+ Details

Name:	us-gaap_ContractualObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in obligation for operating lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-SubTopic 20
-Topic 842
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-8

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(1)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

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

- Details

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- Details

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Commitments and Contingencies - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) ft²	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) ft² Days	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Commitments And Contingencies [Line Items]
Decrease in lease liability			$ (3,536)
Operating lease, decrease in right-of-use asset due to re-measurement from lease amendment			3,536
Restricted cash	$ 3,993		3,993		$ 2,563
Guarantee income	118	$ 348	481	$ 1,508
Maximum potential amount of future payments required to make under guarantees	3,780		3,780		$ 10,158
Lease Remeasurement
Commitments And Contingencies [Line Items]
Decrease in lease liability			1,493
Operating lease, decrease in right-of-use asset due to re-measurement from lease amendment			1,493
1001 Boylston Street
Commitments And Contingencies [Line Items]
Contract commitments	$ 4,581		4,581
Increase in tenant improvement allowance			456
Expected to incur additional costs for remaining construction			$ 5,580
Area of land \| ft²	225,428		225,428
Car Offer
Commitments And Contingencies [Line Items]
Guarantees, description			provides certain guarantees to dealers through products such as its 45-Day Guarantee and OfferGuard service offerings on the CarOffer platform, which are accounted for under ASC Topic 460, Guarantees.
Number of days guarantee period \| Days			45