Intangible Assets and Goodwill - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 23,619	$ 26,570
Accumulated Amortization	(10,289)	(10,875)
Net Carrying Amount	13,330	15,695
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,447	20,333
Accumulated Amortization	(6,611)	(7,586)
Net Carrying Amount	10,836	12,747
Customer Relationship Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,699	5,699
Accumulated Amortization	(3,419)	(3,061)
Net Carrying Amount	2,280	2,638
Mortgage Servicing Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	473	538
Accumulated Amortization	(259)	(228)
Net Carrying Amount	$ 214	$ 310