Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair value assets transfers	$ 0	$ 0
Increase in fair value of liabilities	$ 2,400,000	$ 2,300,000

Amount of increase (decrease) in fair value adjustment on other assets (liabilities) carried at fair value under the fair value option on the statement of cash flows of Federal Home Loan Banks (FHLBanks).

No definition available.

Name:	us-gaap_IncreaseDecreaseInFairValueAdjustmentsOnAssetsAndLiabilitiesCarriedAtFairValueUnderFairValueOption
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration