Allowance for Credit Losses - Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Allowance for loan and lease losses:
Balance at beginning of period	$ 169,148	$ 192,120	$ 208,454	$ 130,530
Charge-offs	(3,385)	(4,836)	(15,300)	(39,639)
Recoveries	2,783	4,920	9,011	10,201
Increase (decrease) in Provision	(7,300)	3,672	(40,919)	94,014
Balance at end of period	161,246	195,876	161,246	195,876
Commercial Lending
Allowance for loan and lease losses:
Balance at beginning of period				4,844
Charge-offs				(379)
Recoveries				170
Increase (decrease) in Provision				2,102
Balance at end of period		4,934		4,934
Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period	23,063	21,299	24,711	28,975
Charge-offs	(224)	(598)	(1,517)	(14,773)
Recoveries	121	1,699	623	2,019
Increase (decrease) in Provision	796	(1,129)	(61)	21,155
Balance at end of period	23,756	21,271	23,756	21,271
Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period	47,033	53,122	58,123	22,325
Charge-offs			(66)	(2,723)
Recoveries	15		30
Increase (decrease) in Provision	(3,449)	(1,389)	(14,488)	21,572
Balance at end of period	43,599	51,733	43,599	51,733
Construction
Allowance for loan and lease losses:
Balance at beginning of period	10,152	5,276	10,039
Recoveries		30	166
Increase (decrease) in Provision	(398)	(372)	(451)
Balance at end of period	9,754	4,934	9,754	4,934
Lease financing
Allowance for loan and lease losses:
Balance at beginning of period	3,067	3,837	3,298	424
Increase (decrease) in Provision	(833)	214	(1,064)	3,420
Balance at end of period	2,234	4,051	2,234	4,051
Unallocated
Allowance for loan and lease losses:
Balance at beginning of period				139
Residential mortgage | Residential
Allowance for loan and lease losses:
Balance at beginning of period	34,208	33,874	40,461	29,303
Charge-offs			(98)	(14)
Recoveries	215	27	246	179
Increase (decrease) in Provision	(655)	8,316	(6,841)	15,542
Balance at end of period	33,768	42,217	33,768	42,217
Home equity | Residential
Allowance for loan and lease losses:
Balance at beginning of period	6,250	7,635	7,163	9,876
Charge-offs	(235)		(235)	(8)
Recoveries	27	16	89	146
Increase (decrease) in Provision	(325)	(50)	(1,300)	2,318
Balance at end of period	5,717	7,601	5,717	7,601
Consumer loans | Consumer
Allowance for loan and lease losses:
Balance at beginning of period	45,375	67,077	64,659	34,644
Charge-offs	(2,926)	(4,238)	(13,384)	(21,742)
Recoveries	2,405	3,148	7,857	7,687
Increase (decrease) in Provision	(2,436)	(1,918)	(16,714)	27,905
Balance at end of period	$ 42,418	$ 64,069	$ 42,418	64,069
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments
Allowance for loan and lease losses:
Balance at beginning of period				770
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Commercial Lending
Allowance for loan and lease losses:
Balance at beginning of period				(1,803)
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period				(16,105)
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period				10,559
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Lease financing
Allowance for loan and lease losses:
Balance at beginning of period				207
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Unallocated
Allowance for loan and lease losses:
Balance at beginning of period				(139)
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Residential mortgage | Residential
Allowance for loan and lease losses:
Balance at beginning of period				(2,793)
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Home equity | Residential
Allowance for loan and lease losses:
Balance at beginning of period				(4,731)
ASU No. 2016-13 | Cumulative-effect adjustment of a change in accounting principle, net of tax: ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Consumer loans | Consumer
Allowance for loan and lease losses:
Balance at beginning of period				$ 15,575