Allowance for Loan and Lease Losses - Roll forward of Allowance for Loan and Lease Losses for PCI and Non-PCI Loans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	$ 45,034	$ 50,211
Charge-offs	(1,824)	(1,899)
Recoveries	678	754
Net charge-offs	(1,146)	(1,145)
Provision (reversal) for loan and lease losses	1,375	(841)
Balance, end of period	45,263	48,225
Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	20,546	21,355
Charge-offs	(1,824)	(1,899)
Recoveries	678	754
Net charge-offs	(1,146)	(1,145)
Provision (reversal) for loan and lease losses	1,384	1,085
Balance, end of period	20,784	21,295
Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	15,978	15,557
Charge-offs	(1)	(8)
Recoveries	12	173
Net charge-offs	11	165
Provision (reversal) for loan and lease losses	345	(14)
Balance, end of period	16,334	15,708
Total commercial real estate | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(1)	(8)
Recoveries	12	173
Provision (reversal) for loan and lease losses	(127)	(205)
Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	11,132	12,006
Charge-offs	(81)	(166)
Recoveries	38	151
Net charge-offs	(43)	(15)
Provision (reversal) for loan and lease losses	727	(199)
Balance, end of period	11,816	11,792
Total commercial | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(81)	(166)
Recoveries	38	151
Provision (reversal) for loan and lease losses	444	88
Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	17,661	22,388
Charge-offs	(1,190)	(1,242)
Recoveries	407	230
Net charge-offs	(783)	(1,012)
Provision (reversal) for loan and lease losses	(67)	(915)
Balance, end of period	16,811	20,461
Total consumer | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(1,190)	(1,242)
Recoveries	407	230
Provision (reversal) for loan and lease losses	729	909
Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	263	260
Charge-offs	(552)	(483)
Recoveries	221	200
Net charge-offs	(331)	(283)
Provision (reversal) for loan and lease losses	370	287
Balance, end of period	302	264
Other | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(552)	(483)
Recoveries	221	200
Provision (reversal) for loan and lease losses	338	293
Non-owner occupied commercial real estate | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	1,598	2,022
Charge-offs	(1)	0
Recoveries	8	3
Net charge-offs	7	3
Provision (reversal) for loan and lease losses	66	(135)
Balance, end of period	1,671	1,890
Non-owner occupied commercial real estate | Total commercial real estate | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(1)	0
Recoveries	8	3
Provision (reversal) for loan and lease losses	(51)	32
Other commercial construction and land | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	12,919	12,181
Charge-offs	0	(8)
Recoveries	3	169
Net charge-offs	3	161
Provision (reversal) for loan and lease losses	274	233
Balance, end of period	13,196	12,575
Other commercial construction and land | Total commercial real estate | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	(8)
Recoveries	3	169
Provision (reversal) for loan and lease losses	(103)	(204)
Multifamily commercial real estate | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	186	252
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Provision (reversal) for loan and lease losses	(4)	(29)
Balance, end of period	182	223
Multifamily commercial real estate | Total commercial real estate | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	(14)	(4)
1-4 family residential construction and land | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	1,275	1,102
Charge-offs	0	0
Recoveries	1	1
Net charge-offs	1	1
Provision (reversal) for loan and lease losses	9	(83)
Balance, end of period	1,285	1,020
1-4 family residential construction and land | Total commercial real estate | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	1	1
Provision (reversal) for loan and lease losses	41	(29)
Owner occupied commercial real estate | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	1,505	2,504
Charge-offs	(80)	(112)
Recoveries	0	0
Net charge-offs	(80)	(112)
Provision (reversal) for loan and lease losses	262	183
Balance, end of period	1,687	2,575
Owner occupied commercial real estate | Total commercial | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(80)	(112)
Recoveries	0	0
Provision (reversal) for loan and lease losses	138	300
Commercial and industrial loans | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	9,627	9,502
Charge-offs	(1)	(54)
Recoveries	38	151
Net charge-offs	37	97
Provision (reversal) for loan and lease losses	465	(382)
Balance, end of period	10,129	9,217
Commercial and industrial loans | Total commercial | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(1)	(54)
Recoveries	38	151
Provision (reversal) for loan and lease losses	306	(213)
Lease financing | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	0	0
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Provision (reversal) for loan and lease losses	0	0
Balance, end of period	0	0
Lease financing | Total commercial | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	0	1
1-4 family residential | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	11,057	15,451
Charge-offs	0	(215)
Recoveries	5	4
Net charge-offs	5	(211)
Provision (reversal) for loan and lease losses	(688)	(1,710)
Balance, end of period	10,374	13,530
1-4 family residential | Total consumer | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	(215)
Recoveries	5	4
Provision (reversal) for loan and lease losses	(100)	107
Home equity loans | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	1,853	2,815
Charge-offs	(61)	(160)
Recoveries	173	92
Net charge-offs	112	(68)
Provision (reversal) for loan and lease losses	(370)	42
Balance, end of period	1,595	2,789
Home equity loans | Total consumer | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(61)	(160)
Recoveries	173	92
Provision (reversal) for loan and lease losses	(155)	55
Other consumer loans | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	4,751	4,122
Charge-offs	(1,129)	(867)
Recoveries	229	134
Net charge-offs	(900)	(733)
Provision (reversal) for loan and lease losses	991	753
Balance, end of period	4,842	4,142
Other consumer loans | Total consumer | Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	(1,129)	(867)
Recoveries	229	134
Provision (reversal) for loan and lease losses	984	747
PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	24,488	28,856
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Provision (reversal) for loan and lease losses	(9)	(1,926)
Balance, end of period	24,479	26,930
PCI Loans | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	472	191
PCI Loans | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	283	(287)
PCI Loans | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	(796)	(1,824)
PCI Loans | Other
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	32	(6)
PCI Loans | Non-owner occupied commercial real estate | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	117	(167)
PCI Loans | Other commercial construction and land | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	377	437
PCI Loans | Multifamily commercial real estate | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	10	(25)
PCI Loans | 1-4 family residential construction and land | Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	(32)	(54)
PCI Loans | Owner occupied commercial real estate | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	124	(117)
PCI Loans | Commercial and industrial loans | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	159	(169)
PCI Loans | Lease financing | Total commercial
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	0	(1)
PCI Loans | 1-4 family residential | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	(588)	(1,817)
PCI Loans | Home equity loans | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	(215)	(13)
PCI Loans | Other consumer loans | Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs	0	0
Recoveries	0	0
Provision (reversal) for loan and lease losses	$ 7	$ 6