Loans and Allowance for Loan Losses - Activity in All by Class of Loans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	$ 41,666	$ 40,889
Charge- offs	(1,280)	(762)
Recoveries	82	96
Net charge- offs	(1,198)	(666)
Provisions charged to operations	4,103	1,334
Balance at end of period	44,571	41,557
Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	4,661	4,406
Charge- offs	(1)	(1)
Recoveries		1
Net charge- offs	(1)
Provisions charged to operations	172	55
Balance at end of period	4,832	4,461
Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	9,921	9,616
Charge- offs	(1)
Recoveries	1
Provisions charged to operations	290	282
Balance at end of period	10,211	9,898
Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	3,148	2,948
Charge- offs	(50)	(40)
Recoveries	17	9
Net charge- offs	(33)	(31)
Provisions charged to operations	49	67
Balance at end of period	3,164	2,984
Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	6,725	6,269
Charge- offs	(67)	(68)
Recoveries	4	5
Net charge- offs	(63)	(63)
Provisions charged to operations	1,327	372
Balance at end of period	7,989	6,578
Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	11,754	12,771
Charge- offs	(803)	(153)
Recoveries	11	31
Net charge- offs	(792)	(122)
Provisions charged to operations	1,851	419
Balance at end of period	12,813	13,068
Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	2,642	2,404
Charge- offs	(221)	(127)
Recoveries	38	15
Net charge- offs	(183)	(112)
Provisions charged to operations	94	35
Balance at end of period	2,553	2,327
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	2,648	2,359
Charge- offs	(133)	(213)
Recoveries	6	9
Net charge- offs	(127)	(204)
Provisions charged to operations	269	86
Balance at end of period	2,790	2,241
Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	167	116
Charge- offs	(4)	(160)
Recoveries	5	26
Net charge- offs	1	(134)
Provisions charged to operations	51	$ 18
Balance at end of period	$ 219