Securities Available-for-Sale - Continuous Unrealized Loss Position for 12 Months or Less and 12 Months or Longer (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 182,481	$ 30,036
Less Than 12 Months, Unrealized Losses	499	67
12 Months or Longer, Fair Value	41,024	55,024
12 Months or Longer, Unrealized Losses	673	1,266
Total, Fair Value	223,505	85,060
Total, Unrealized Losses	1,172	1,333
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		1,989
Less Than 12 Months, Unrealized Losses		10
Total, Fair Value		1,989
Total, Unrealized Losses		10
SBA Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	52,809	1,031
Less Than 12 Months, Unrealized Losses	160	2
12 Months or Longer, Fair Value	971
12 Months or Longer, Unrealized Losses	2
Total, Fair Value	53,780	1,031
Total, Unrealized Losses	162	2
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	128,839	26,519
Less Than 12 Months, Unrealized Losses	298	52
12 Months or Longer, Fair Value	33,439	49,341
12 Months or Longer, Unrealized Losses	139	248
Total, Fair Value	162,278	75,860
Total, Unrealized Losses	437	300
Privately Issued Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	373
Less Than 12 Months, Unrealized Losses	1
12 Months or Longer, Fair Value	430	490
12 Months or Longer, Unrealized Losses	14	13
Total, Fair Value	803	490
Total, Unrealized Losses	15	13
Obligations Issued by States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or Longer, Fair Value	4,298	3,820
12 Months or Longer, Unrealized Losses	404	878
Total, Fair Value	4,298	3,820
Total, Unrealized Losses	404	878
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	460	497
Less Than 12 Months, Unrealized Losses	40	3
12 Months or Longer, Fair Value	1,886	1,373
12 Months or Longer, Unrealized Losses	114	127
Total, Fair Value	2,346	1,870
Total, Unrealized Losses	$ 154	$ 130