Allowance Allocations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 55,825				$ 55,100	$ 55,825	$ 55,100	$ 53,239
Charge-offs									(3,472)	(4,918)	(10,947)
Recoveries									3,138	4,143	2,405
Provision (benefit)	$ 4,000	$ 950	$ 600	525	$ 500	$ 800	$ 700	(500)	6,075	1,500	10,403
Ending balance	61,566				55,825				61,566	55,825	55,100
Ending balance: individually evaluated for impairment	5,214				1,930				5,214	1,930	2,416
Ending balance: collectively evaluated for impairment	56,352				53,895				56,352	53,895	52,684
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	5,903,916				5,475,716				5,903,916	5,475,716	4,890,383
Individually evaluated for impairment	77,297				51,410				77,297	51,410	58,035
Financing Receivable, Net	4,355,968				3,966,324				4,355,968	3,966,324
Loans Receivable, Gross, Commercial and Industrial	902,053				843,276				902,053	843,276
Loans Receivable, Gross, Commercial, Mortgage	3,010,798				2,653,434				3,010,798	2,653,434
Total loans	5,999,605				5,547,721				5,999,605	5,547,721	4,970,733	[1]
Loans and Leases Receivable, Gross, Consumer, Other	11,064				14,988				11,064	14,988
Loans Receivable, Gross, Commercial, Construction	320,391				373,368				320,391	373,368
Small Business	122,726				96,246				122,726	96,246
Loans and Leases Receivable, Gross, Consumer, Mortgage	644,426				638,606				644,426	638,606
Commercial and Industrial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				13,802				15,573	13,802	15,573	15,622
Charge-offs									(593)	(2,010)	(2,097)
Recoveries									859	1,593	462
Provision (benefit)									2,853	(1,354)	1,586
Ending balance	16,921				13,802				16,921	13,802	15,573
Ending balance: individually evaluated for impairment	3,661				183				3,661	183	412
Ending balance: collectively evaluated for impairment	13,260				13,619				13,260	13,619	15,161
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	862,875				838,129				862,875	838,129	856,185
Individually evaluated for impairment	39,178				5,147				39,178	5,147	4,654
Financing Receivable, Net	902,053				843,276				902,053	843,276
Total loans	902,053				843,276				902,053	843,276	860,839
Commercial Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				27,327				25,873	27,327	25,873	24,541
Charge-offs									(414)	(330)	(5,454)
Recoveries									564	1,073	404
Provision (benefit)									2,892	711	6,382
Ending balance	30,369				27,327				30,369	27,327	25,873
Ending balance: individually evaluated for impairment	196				204				196	204	197
Ending balance: collectively evaluated for impairment	30,173				27,123				30,173	27,123	25,676
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	2,983,642				2,619,294				2,983,642	2,619,294	2,304,099
Individually evaluated for impairment	16,813				22,986				16,813	22,986	30,729
Financing Receivable, Net	3,010,798				2,653,434				3,010,798	2,653,434
Total loans	3,010,798				2,653,434				3,010,798	2,653,434	2,347,323
Construction Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				5,366				3,945	5,366	3,945	3,371
Charge-offs									0	0	0
Recoveries									0	0
Provision (benefit)									(844)	1,421	574
Ending balance	4,522				5,366				4,522	5,366	3,945
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	4,522				5,366				4,522	5,366	3,945
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	320,391				373,064				320,391	373,064	265,501
Individually evaluated for impairment	0				304				0	304	311
Financing Receivable, Net	320,391				373,368				320,391	373,368
Total loans	320,391				373,368				320,391	373,368	265,994
Small Business [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				1,264				1,171	1,264	1,171	1,215
Charge-offs									(228)	(267)	(605)
Recoveries									195	264	275
Provision (benefit)									271	96	286
Ending balance	1,502				1,264				1,502	1,264	1,171
Ending balance: individually evaluated for impairment	8				4				8	4	7
Ending balance: collectively evaluated for impairment	1,494				1,260				1,494	1,260	1,164
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	121,855				95,225				121,855	95,225	84,159
Individually evaluated for impairment	871				1,021				871	1,021	1,088
Financing Receivable, Net	122,726				96,246				122,726	96,246
Total loans	122,726				96,246				122,726	96,246	85,247
Residential Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				2,590				2,834	2,590	2,834	2,760
Charge-offs									(28)	(285)	(826)
Recoveries									299	133	424
Provision (benefit)									(240)	(92)	476
Ending balance	2,621				2,590				2,621	2,590	2,834
Ending balance: individually evaluated for impairment	1,086				1,278				1,086	1,278	1,500
Ending balance: collectively evaluated for impairment	1,535				1,312				1,535	1,312	1,334
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	622,392				614,014				622,392	614,014	505,799
Individually evaluated for impairment	14,175				15,405				14,175	15,405	15,055
Total loans	644,426				638,606				644,426	638,606	530,259
Home Equity [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				4,889				4,956	4,889	4,956	5,036
Charge-offs									(602)	(710)	(750)
Recoveries									141	356	249
Provision (benefit)									810	287	421
Ending balance	5,238				4,889				5,238	4,889	4,956
Ending balance: individually evaluated for impairment	242				238				242	238	262
Ending balance: collectively evaluated for impairment	4,996				4,651				4,996	4,651	4,694
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	982,095				921,563				982,095	921,563	858,305
Individually evaluated for impairment	5,863				5,989				5,863	5,989	5,330
Total loans	988,147				927,803				988,147	927,803	863,863
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 587				$ 748	587	748	694
Charge-offs									(1,607)	(1,316)	(1,215)
Recoveries									1,080	724	591
Provision (benefit)									333	431	678
Ending balance	393				587				393	587	748
Ending balance: individually evaluated for impairment	21				23				21	23	38
Ending balance: collectively evaluated for impairment	372				564				372	564	710
Financing receivables ending balance:
Financing Receivable, Collectively Evaluated for Impairment	10,666				14,427				10,666	14,427	16,335
Individually evaluated for impairment	397				558				397	558	868
Total loans	11,064				14,988				11,064	14,988	17,208
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing receivables ending balance:
Financing Receivable, Net	18,392				20,595				18,392	20,595	22,315
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial and Industrial [Member]
Financing receivables ending balance:
Financing Receivable, Net	0				0				0	0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Real Estate [Member]
Financing receivables ending balance:
Financing Receivable, Net	10,343				11,154				10,343	11,154	12,495
Receivables Acquired with Deteriorated Credit Quality [Member] | Construction Loans [Member]
Financing receivables ending balance:
Financing Receivable, Net	0				0				0	0	182
Receivables Acquired with Deteriorated Credit Quality [Member] | Small Business [Member]
Financing receivables ending balance:
Financing Receivable, Net	0				0				0	0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Residential Real Estate [Member]
Financing receivables ending balance:
Financing Receivable, Net	7,859				9,187				7,859	9,187	9,405
Receivables Acquired with Deteriorated Credit Quality [Member] | Home Equity [Member]
Financing receivables ending balance:
Financing Receivable, Net	189				251				189	251	228
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer Portfolio Segment [Member]
Financing receivables ending balance:
Financing Receivable, Net	$ 1				$ 3				$ 1	$ 3	$ 5

[1] The amount of net deferred costs on originated loans included in the ending balance was $5.1 million, $4.3 million, and $2.8 million at December 31, 2016, 2015, and 2014, respectively. Net unamortized discounts on acquired loans not deemed to be PCI included in the ending balance was $8.6 million, $6.6 million, and $1.9 million at December 31, 2016, 2015, and 2014, respectively.