Fair value measurements - Assets and liabilities measured at fair value on a recurring basis (Detail)	Dec. 31, 2025 CNY (¥)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 CNY (¥)
Assets:
Short-term investments	¥ 879,224,792	$ 125,727,473	¥ 1,118,547,455
Derivative instruments	113,191,365	16,186,150
Liabilities:
Derivative instruments	52,011,906	7,437,604	89,894,630
Fair value, recurring
Assets:
Short-term investments	879,224,792	125,727,473	1,118,547,455
Long-term investments without readily determinable fair value using NAV practical expedient	14,700,093	2,102,085	15,163,357
Derivative instruments	113,191,365	16,186,150
Liabilities:
Derivative instruments	52,011,906	7,437,604	89,894,630
Active market (Level 1) \| Fair value, recurring
Assets:
Short-term investments	768,234,872	109,856,126	1,091,582,140
Observable input (Level 2) \| Fair value, recurring
Assets:
Short-term investments	110,989,920	15,871,348	26,965,315
Derivative instruments	113,191,365	16,186,150
Liabilities:
Derivative instruments	¥ 52,011,906	$ 7,437,604	¥ 89,894,630

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-10

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Amount of investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479536/321-10-50-3

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- Definition

Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

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-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

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