Fair Value Measurement - Reconciliation of Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) on Recurring Basis (Detail) - Mortgage servicing rights - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 4,250	$ 6,229	$ 6,200	$ 7,098
Transfers into (out of) Level 3	0	0	0	0
Change Included in Earnings	236	(455)	(2,258)	(1,652)
Issuances	434	298	978	626
Ending Balance	$ 4,920	$ 6,072	$ 4,920	$ 6,072