Loans and Leases - Credit Risk Profile by Internally Assigned Grade (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	$ 3,381,475	$ 3,285,858
Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,752,160	2,487,296
Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,458,984	2,395,234
Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,016,075	1,827,327
Pass | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	442,909	567,907
Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	5,680	18,239
Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,198	664
Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	3,482	17,575
Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	54,769	39,532
Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	18,014	11,551
Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	36,755	27,981
Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	552	2,138
Doubtful | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1	355
Doubtful | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	551	1,783
Pass, Special Mention and Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,519,985	2,455,143
Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,036,288	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	483,697	615,246
Commercial mortgage
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,618,493	1,523,377
Commercial mortgage | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,259,397	1,122,327
Commercial mortgage | Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,592,174	1,490,862
Commercial mortgage | Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,252,916	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	339,258	376,691
Commercial mortgage | Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,321	13,448
Commercial mortgage | Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	0
Commercial mortgage | Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,321	13,448
Commercial mortgage | Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	23,447	18,194
Commercial mortgage | Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	6,481	8,156
Commercial mortgage | Substandard | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	16,966	10,038
Commercial mortgage | Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	551	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	551	873
Commercial mortgage | Pass, Special Mention and Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,618,493	1,523,377
Commercial mortgage | Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,259,397	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	359,096	401,050
Construction
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	178,493	212,454
Construction | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	158,691	128,266
Construction | Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	168,897	193,227
Construction | Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	152,429	126,260
Construction | Pass | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	16,468	66,967
Construction | Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	934	3,902
Construction | Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	0	0
Construction | Special Mention | Financial Asset Acquired With and Without Credit Deterioration
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	934	3,902
Construction | Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	8,662	15,325
Construction | Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	6,262	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	178,493	212,454
Construction | Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	158,691	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	19,802	84,188
Real estate loans
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,472,194	2,412,992
Real estate loans | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1,979,193	1,794,811
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	722,999	719,312
Commercial and industrial | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	618,200	589,304
Commercial and industrial | Pass
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	697,913	711,145
Commercial and industrial | Pass | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	610,730	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	87,183	124,249
Commercial and industrial | Special Mention
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,425	889
Commercial and industrial | Special Mention | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	2,198	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	227	225
Commercial and industrial | Substandard
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	22,660	6,013
Commercial and industrial | Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	5,271	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	17,389	4,624
Commercial and industrial | Doubtful
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1	1,265
Commercial and industrial | Doubtful | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	1	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	722,999	719,312
Commercial and industrial | Pass, Special Mention and Substandard | Originated
Loans and Leases Receivable Disclosure [Line Items]
Portfolio loans and leases	618,200	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	$ 104,799	$ 130,008