Loans and Allowance for Loan Losses - Summary of Aging of Loans (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Loan premiums	$ 2,717	$ 5,758
Capitalized loan origination costs	$ 21,345	$ 18,403

Amount of unearned premiums on outstanding advances made and reported by Federal Home Loan Bank (FHLBank).

No definition available.

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