Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 166,209	$ 169,410	$ 176,084
Loans charged off	30,557
Recoveries of loans previously charged off	21,020
Net loans recovered (charged off)	(9,537)
Provision for credit losses	76,920
Ending balance	291,940	166,209	169,410
Loans charged off		(53,189)	(66,076)
Recoveries of loans previously charged off		17,163	12,495
Net loans recovered (charged off)		(36,026)	(53,581)
Provision for credit losses	76,920	32,825	46,907
Provision for loan losses		39,111
ACL - loans	277,567	163,622	160,537
Real estate - commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(1,837)
Recoveries of loans previously charged off		2,202
Net loans recovered (charged off)		365
Provision for loan losses		(7,644)
ACL - loans		45,610	52,889
Commercial and industrial (1)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(42,410)
Recoveries of loans previously charged off		8,721
Net loans recovered (charged off)		(33,689)
Provision for loan losses		43,423
ACL - loans		68,602	58,868
Real estate - home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(1,291)
Recoveries of loans previously charged off		688
Net loans recovered (charged off)		(603)
Provision for loan losses		(564)
ACL - loans		17,744	18,911
Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(1,545)
Recoveries of loans previously charged off		989
Net loans recovered (charged off)		(556)
Provision for loan losses		1,406
ACL - loans		19,771	18,921
Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(143)
Recoveries of loans previously charged off		2,591
Net loans recovered (charged off)		2,448
Provision for loan losses		(3,066)
ACL - loans		4,443	5,061
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(3,403)
Recoveries of loans previously charged off		1,306
Net loans recovered (charged off)		(2,097)
Provision for loan losses		2,642
ACL - loans		3,762	3,217
Leasing and other and overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		(2,560)
Recoveries of loans previously charged off		666
Net loans recovered (charged off)		(1,894)
Provision for loan losses		2,914
ACL - loans		3,690	$ 2,670
Cumulative Effect, Period of Adoption, Adjustment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	58,348
Ending balance		58,348
Loans - Excluding OBS Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	163,622
Loans charged off	30,557
Recoveries of loans previously charged off	21,020
Net loans recovered (charged off)	(9,537)
Provision for credit losses	77,760
Ending balance	277,567	163,622
Loans - Excluding OBS Credit Exposure [Member] | Real estate - commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	45,610
Loans charged off	4,225
Recoveries of loans previously charged off	1,027
Net loans recovered (charged off)	(3,198)
Provision for credit losses	31,652
Ending balance	103,425	45,610
Loans - Excluding OBS Credit Exposure [Member] | Commercial and industrial (1)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	68,602
Loans charged off	18,915
Recoveries of loans previously charged off	11,396
Net loans recovered (charged off)	(7,519)
Provision for credit losses	32,264
Ending balance	74,771	68,602
Loans - Excluding OBS Credit Exposure [Member] | Real estate - home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	17,744
Loans charged off	1,193
Recoveries of loans previously charged off	504
Net loans recovered (charged off)	(689)
Provision for credit losses	(2,758)
Ending balance	14,232	17,744
Loans - Excluding OBS Credit Exposure [Member] | Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	19,771
Loans charged off	620
Recoveries of loans previously charged off	491
Net loans recovered (charged off)	(129)
Provision for credit losses	11,118
Ending balance	51,995	19,771
Loans - Excluding OBS Credit Exposure [Member] | Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	4,443
Loans charged off	17
Recoveries of loans previously charged off	5,122
Net loans recovered (charged off)	5,105
Provision for credit losses	2,045
Ending balance	15,608	4,443
Loans - Excluding OBS Credit Exposure [Member] | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	3,762
Loans charged off	3,400
Recoveries of loans previously charged off	1,875
Net loans recovered (charged off)	(1,525)
Provision for credit losses	2,699
Ending balance	10,905	3,762
Loans - Excluding OBS Credit Exposure [Member] | Leasing and other and overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	3,690
Loans charged off	2,187
Recoveries of loans previously charged off	605
Net loans recovered (charged off)	(1,582)
Provision for credit losses	741
Ending balance	6,633	3,690
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	45,723
Ending balance		45,723
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Real estate - commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	29,361
Ending balance		29,361
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Commercial and industrial (1)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	(18,576)
Ending balance		(18,576)
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Real estate - home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	(65)
Ending balance		(65)
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	21,235
Ending balance		21,235
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	4,015
Ending balance		4,015
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	5,969
Ending balance		5,969
Loans - Excluding OBS Credit Exposure [Member] | Cumulative Effect, Period of Adoption, Adjustment | Leasing and other and overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 3,784
Ending balance		$ 3,784