Securities Available-for-Sale - Summary of Securities Available-for-Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 500,220	$ 404,977
Gross Unrealized Gains	555	979
Gross Unrealized Losses	1,478	1,333
Total, Fair Value	499,297	404,623
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,000	1,999
Gross Unrealized Losses		10
Total, Fair Value	2,000	1,989
U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25,000
Gross Unrealized Losses	48
Total, Fair Value	24,952
SBA Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	57,899	5,983
Gross Unrealized Gains	14	8
Gross Unrealized Losses	146	2
Total, Fair Value	57,767	5,989
U.S. Government Agency and Sponsored Enterprises Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	243,703	232,967
Gross Unrealized Gains	293	859
Gross Unrealized Losses	671	300
Total, Fair Value	243,325	233,526
Privately Issued Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,121	1,437
Gross Unrealized Gains	2	10
Gross Unrealized Losses	14	13
Total, Fair Value	1,109	1,434
Obligations Issued by States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	165,281	157,838
Gross Unrealized Losses	405	878
Total, Fair Value	164,876	156,960
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,100	4,600
Gross Unrealized Gains	18	3
Gross Unrealized Losses	194	130
Total, Fair Value	4,924	4,473
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	116	153
Gross Unrealized Gains	228	99
Total, Fair Value	$ 344	$ 252