Investment Securities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 USD ($) Times Security	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of securities prior to maturity | Security	2
Gross proceed from sale of securities	$ 206,000
Gross realized gains	4,000
OTTI credit related charge	0	$ 0
Cumulative OTTI balance	1,200,000
OTTI charges recognized in earnings	0	$ 0
Less than 12 months gross unrealized loss	2,091,000		$ 1,709,000
Less than 12 Months, Estimated Fair Value	190,856,000		109,045,000
Gross unrealized loss in the category of 12 months or longer	2,028,000		3,224,000
12 Months or longer estimated fair value	29,626,000		98,433,000
Investment grade rated pooled security with an amortized cost	$ 48,259,000		53,378,000
Future default rate	3.60%
Period of time with no recovery rate	3 years
Amortized cost of investment securities pledged to secure public deposits	$ 12,900,000
Estimated fair value of investment securities pledged to secure public deposits	12,900,000
Amortized cost of investment securities pledged as collateral on secured borrowings	63,700,000
Estimated fair value of investment securities pledged as collateral on secured borrowings	63,500,000
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months gross unrealized loss	$ 3,000
Number of investment securities in unrealized loss less than 12 months | Security	2
Less than 12 Months, Estimated Fair Value	$ 3,497,000
U.S. Government Agency Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months gross unrealized loss	$ 2,061,000		1,683,000
Number of investment securities in unrealized loss less than 12 months | Security	37
Less than 12 Months, Estimated Fair Value	$ 164,398,000		108,070,000
Gross unrealized loss in the category of 12 months or longer	$ 435,000		892,000
Number of investment securities in unrealized loss position of twelve months or longer | Security	4
12 Months or longer estimated fair value	$ 11,196,000		54,757,000
Collateralized Loan Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months gross unrealized loss	2,000
Less than 12 Months, Estimated Fair Value	21,986,000
Gross unrealized loss in the category of 12 months or longer	14,000		160,000
12 Months or longer estimated fair value	$ 7,985,000		33,825,000
Collateralized Loan Obligations [Member] | AAA [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities in unrealized loss less than 12 months | Security	2
Number of investment securities in unrealized loss position of twelve months or longer | Security	1
Trust Preferred Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cumulative OTTI balance	$ 1,200,000
Gross unrealized loss in the category of 12 months or longer	$ 1,579,000		2,172,000
Number of investment securities in unrealized loss position of twelve months or longer | Security	2
12 Months or longer estimated fair value	$ 10,445,000		$ 9,851,000
Number of Non-rated single issuer security | Security	1
Non-rated single issuer security with amortized cost	$ 3,200,000
Non-rated single issuer security, estimated fair value	$ 3,200,000
Number of investment grade rated pooled security | Security	1
Investment grade rated pooled security with an amortized cost	$ 8,800,000
Investment grade rated pooled security, estimated fair value	$ 7,200,000
Security with principal coverage | Times	3.7
Called Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities called | Security	2
Aggregate par value of securities called	$ 6,000,000