Allowance for Credit Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) loan SecurityLoan	Dec. 31, 2020 USD ($) SecurityLoan loan	Dec. 31, 2019 USD ($)
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	$ 6,999,990	$ 7,225,860
Non- performing	$ 66,291	$ 146,774	$ 54,057
CARES Act, Paycheck Protection Program Loans
Financing Receivable, Past Due [Line Items]
Number of modified loans | loan	8	52
Modified loans	$ 28,800	$ 195,600
Current
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	6,927,943	7,069,730
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	3,085	2,888
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	2,672	5,965
90 Days + Past Due
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		503
Total Past Due Loans
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	$ 72,048	$ 156,130
Commercial | CARES Act, Paycheck Protection Program Loans
Financing Receivable, Past Due [Line Items]
Number of modified loans | SecurityLoan	8	52
Modified loans	$ 28,800	$ 195,600
Commercial | Commercial real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	2,690,528	2,791,947
Non- performing	31,488	101,070	25,356
Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,513,523	1,559,552
Non- performing	15,239	16,985	10,911
Commercial | Commercial construction
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	424,755	466,077
Non- performing	2,471	384	737
Commercial | Business banking
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,135,693	1,160,067
Non- performing	9,641	17,122	9,863
Commercial | Current | Commercial real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	2,659,040	2,690,877
Commercial | Current | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,497,755	1,542,567
Commercial | Current | Commercial construction
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	421,834	462,094
Commercial | Current | Business banking
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,124,748	1,140,581
Commercial | 30-59 Days Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	0	0
Commercial | 30-59 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	529	0
Commercial | 30-59 Days Past Due | Commercial construction
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	450	19
Commercial | 30-59 Days Past Due | Business banking
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	813	1,614
Commercial | 60-89 Days Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	0	0
Commercial | 60-89 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	0	0
Commercial | 60-89 Days Past Due | Commercial construction
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	0	3,580
Commercial | 60-89 Days Past Due | Business banking
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	491	379
Commercial | 90 Days + Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		0
Commercial | 90 Days + Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		0
Commercial | 90 Days + Past Due | Commercial construction
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		0
Commercial | 90 Days + Past Due | Business banking
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		371
Commercial | Total Past Due Loans | Commercial real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	31,488	101,070
Commercial | Total Past Due Loans | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	15,768	16,985
Commercial | Total Past Due Loans | Commercial construction
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	2,921	3,983
Commercial | Total Past Due Loans | Business banking
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	10,945	19,486
Consumer | Consumer real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,127,585	1,167,332
Non- performing	7,294	11,117	6,063
Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	107,906	80,885
Non- performing	158	96	$ 1,127
Consumer | Current | Consumer real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,117,073	1,153,028
Consumer | Current | Other consumer
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	107,492	80,583
Consumer | 30-59 Days Past Due | Consumer real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	1,087	1,087
Consumer | 30-59 Days Past Due | Other consumer
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	206	168
Consumer | 60-89 Days Past Due | Consumer real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	2,130	1,968
Consumer | 60-89 Days Past Due | Other consumer
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	50	37
Consumer | 90 Days + Past Due | Consumer real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		132
Consumer | 90 Days + Past Due | Other consumer
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income		0
Consumer | Total Past Due Loans | Consumer real estate
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	10,512	14,304
Consumer | Total Past Due Loans | Other consumer
Financing Receivable, Past Due [Line Items]
Portfolio loans, net of unearned income	$ 414	$ 302