Loans Held for Investment and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Detail) - USD ($) $ in Thousands		Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Receivables [Abstract]
Non-accrual loans		$ 25,475	$ 31,652	$ 29,786
Loans still accruing and past due 90 days or more		22	8	0
Troubled debt restructured loans still accruing	[1]	20	21	23
Total		$ 25,517	$ 31,681	$ 29,809

[1] Troubled debt restructured loans of $2,242,000, $7,305,000 and $6,721,000, for which interest collection is doubtful are included in nonaccrual loans as of June 30, 2022 and 2021, and December 31, 2021, respectively.