Goodwill and Other Intangible Assets - Summary of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Balance of intangible assets, Gross CDI Carrying Amount, Beginning of period	$ 34,089	$ 34,089
Additions due to acquisitions	3,851
Balance of intangible assets, Gross CDI Carrying Amount, End of period	37,940	34,089
Aggregate amortization expense, Gross CDI Carrying Amount	1,106	949
Estimated Amortization Expense:
Estimated Amortization Expense, 2017	1,066
Estimated Amortization Expense, 2018	989
Estimated Amortization Expense, 2019	751
Estimated Amortization Expense, 2020	402
Estimated Amortization Expense, Thereafter	1,802
Balance of intangible assets, Accumulated Amortization, Beginning of period	(31,824)	(30,875)
Balance of intangible assets, Accumulated Amortization, End of period	(32,930)	(31,824)
Balance of intangible assets, Net CDI Amount, Beginning of period	2,265	3,214
Balance of intangible assets, Net CDI Amount, End of period	$ 5,010	$ 2,265