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 [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 6,572	$ 6,953	$ 7,098	$ 6,687
Change Included in Earnings	(552)	(36)	(1,197)	75
Issuances	209	104	328	259
Ending Balance	$ 6,229	$ 7,021	$ 6,229	$ 7,021