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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 5,603	$ 4,250	$ 5,092	$ 6,200
Transfers into (out of) Level 3	0	0		0
Change Included in Earnings	(233)	236	(691)	(2,258)
Issuances	366	434	1,335	978
Ending Balance	$ 5,736	$ 4,920	$ 5,736	$ 4,920