Loans and Leases - Credit Risk Profile by Internally Assigned Grade (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	$ 3,389,501	$ 3,285,858
Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,700,814	2,487,296
Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,491,897	2,395,234
Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,999,442	1,827,327
Pass | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	492,455	567,907
Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	4,795	18,239
Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,269	664
Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,526	17,575
Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	52,375	39,532
Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	16,457	11,551
Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	35,918	27,981
Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	834	2,138
Doubtful | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	270	355
Doubtful | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	564	1,783
Pass, Special Mention and Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,549,901	2,455,143
Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,018,438	1,839,897
Pass, Special Mention and Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	531,463	615,246
Commercial mortgage
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,613,721	1,523,377
Commercial mortgage | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,237,885	1,122,327
Commercial mortgage | Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,585,083	1,490,862
Commercial mortgage | Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,228,319	1,114,171
Commercial mortgage | Pass | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	356,764	376,691
Commercial mortgage | Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,357	13,448
Commercial mortgage | Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	990	0
Commercial mortgage | Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,367	13,448
Commercial mortgage | Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	25,717	18,194
Commercial mortgage | Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	8,576	8,156
Commercial mortgage | Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	17,141	10,038
Commercial mortgage | Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	564	873
Commercial mortgage | Doubtful | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	0
Commercial mortgage | Doubtful | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	564	873
Commercial mortgage | Pass, Special Mention and Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,613,721	1,523,377
Commercial mortgage | Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,237,885	1,122,327
Commercial mortgage | Pass, Special Mention and Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	375,836	401,050
Construction
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	190,874	212,454
Construction | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	147,636	128,266
Construction | Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	180,805	193,227
Construction | Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	140,896	126,260
Construction | Pass | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	39,909	66,967
Construction | Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,208	3,902
Construction | Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,279	0
Construction | Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	929	3,902
Construction | Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	7,861	15,325
Construction | Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	5,461	2,006
Construction | Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,400	13,319
Construction | Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	0
Construction | Doubtful | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	0
Construction | Doubtful | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	0
Construction | Pass, Special Mention and Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	190,874	212,454
Construction | Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	147,636	128,266
Construction | Pass, Special Mention and Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	43,238	84,188
Real estate loans
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,460,084	2,412,992
Real estate loans | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,920,563	1,794,811
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	745,306	719,312
Commercial and industrial | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	632,917	589,304
Commercial and industrial | Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	726,009	711,145
Commercial and industrial | Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	630,227	586,896
Commercial and industrial | Pass | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	95,782	124,249
Commercial and industrial | Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	230	889
Commercial and industrial | Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	664
Commercial and industrial | Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	230	225
Commercial and industrial | Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	18,797	6,013
Commercial and industrial | Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,420	1,389
Commercial and industrial | Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	16,377	4,624
Commercial and industrial | Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	270	1,265
Commercial and industrial | Doubtful | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	270	355
Commercial and industrial | Doubtful | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	910
Commercial and industrial | Pass, Special Mention and Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	745,306	719,312
Commercial and industrial | Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	632,917	589,304
Commercial and industrial | Pass, Special Mention and Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	$ 112,389	$ 130,008