Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Loss Contingencies [Line Items]
Loan purchase obligation period	2 days
Contingent loan purchase commitment limit			$ 13,800
Commitment repurchases	$ 900	$ 2,800
Deposit	9,000		9,000
Loan purchase obligation	18,900	$ 28,900
Fair value	7,300		4,500
Contingent liabilities	2,540		21,592
Unfunded Loan Commitment, Commitments To Extend Credit
Loss Contingencies [Line Items]
Unfunded loan commitments	$ 115,500
FTC Lawsuit
Loss Contingencies [Line Items]
Contingent liabilities			$ 18,000