Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 18, 2020	Jul. 31, 2020	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Commitments and Contingencies [Line Items]
Loan purchase obligation period				2 days
Contingent loan purchase commitment limit			$ 3,200	$ 3,200		$ 91,300
Commitment repurchases			275	1,900	$ 3,100
Deposit			9,000	9,000		9,000
Loan purchase obligation				21,500
Fair value			45,600	45,600		45,700
Contingent liabilities			16,375	16,375		$ 16,000
Subsequent Event
Commitments and Contingencies [Line Items]
Commitment repurchases		$ 4
Radius Bancorp, Inc. Merger
Commitments and Contingencies [Line Items]
Value of cash and stock transaction	$ 185,000
Contingent purchase price and expense adjustments	$ 22,000
Acquisition-related Agreements
Commitments and Contingencies [Line Items]
Contingent purchase price and expense adjustments			$ 3,000	$ 3,000