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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 6,229	$ 7,021	$ 7,098	$ 6,687
Change Included in Earnings	(455)	(37)	(1,652)	38
Issuances	298	138	626	397
Ending Balance	$ 6,072	$ 7,122	$ 6,072	$ 7,122