Allowance for Credit Losses - Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Allowance for loan and lease losses:
Balance at beginning of period	$ 200,366	$ 166,013	$ 208,454	$ 130,530
Charge-offs	(4,247)	(25,997)	(11,915)	(34,803)
Recoveries	3,148	2,611	6,228	5,281
Increase (decrease) in Provision	(30,119)	49,493	(33,619)	90,342
Balance at end of period	169,148	192,120	169,148	192,120
Commercial Lending
Allowance for loan and lease losses:
Balance at beginning of period				4,844
Charge-offs				(379)
Recoveries				140
Increase (decrease) in Provision				2,474
Balance at end of period		5,276		5,276
Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period	27,322	20,884	24,711	28,975
Charge-offs	(330)	(13,974)	(1,293)	(14,175)
Recoveries	287	100	502	320
Increase (decrease) in Provision	(4,216)	14,289	(857)	22,284
Balance at end of period	23,063	21,299	23,063	21,299
Commercial Real Estate
Allowance for loan and lease losses:
Balance at beginning of period	51,691	42,838	58,123	22,325
Charge-offs		(2,723)	(66)	(2,723)
Recoveries	12		15
Increase (decrease) in Provision	(4,670)	13,007	(11,039)	22,961
Balance at end of period	47,033	53,122	47,033	53,122
Construction
Allowance for loan and lease losses:
Balance at beginning of period	10,552	8,824	10,039
Charge-offs		(379)
Recoveries		30	166
Increase (decrease) in Provision	(400)	(3,199)	(53)
Balance at end of period	10,152	5,276	10,152	5,276
Lease financing
Allowance for loan and lease losses:
Balance at beginning of period	3,197	851	3,298	424
Increase (decrease) in Provision	(130)	2,986	(231)	3,206
Balance at end of period	3,067	3,837	3,067	3,837
Total
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	38,471	30,021	40,461	29,303
Charge-offs		(14)	(98)	(14)
Recoveries	14	17	31	152
Increase (decrease) in Provision	(4,277)	3,850	(6,186)	7,226
Balance at end of period	34,208	33,874	34,208	33,874
Home equity | Residential
Allowance for loan and lease losses:
Balance at beginning of period	6,668	6,556	7,163	9,876
Charge-offs				(8)
Recoveries	38	8	62	130
Increase (decrease) in Provision	(456)	1,071	(975)	2,368
Balance at end of period	6,250	7,635	6,250	7,635
Consumer loans | Consumer
Allowance for loan and lease losses:
Balance at beginning of period	62,465	56,039	64,659	34,644
Charge-offs	(3,917)	(8,907)	(10,458)	(17,504)
Recoveries	2,797	2,456	5,452	4,539
Increase (decrease) in Provision	(15,970)	17,489	(14,278)	29,823
Balance at end of period	$ 45,375	$ 67,077	$ 45,375	67,077
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 | Total
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