Allowance for Credit Losses - Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for loan and lease losses:
Balance at beginning of period	$ 208,454	$ 130,530
Charge-offs		(8,806)
Recoveries		2,670
Increase (decrease) in Provision		40,849
Balance at end of period	200,366	166,013
Commercial Lending
Allowance for loan and lease losses:
Balance at beginning of period		4,844
Recoveries		110
Increase (decrease) in Provision		5,673
Balance at end of period		8,824
Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period	24,711	28,975
Charge-offs	(963)	(201)
Recoveries	215	220
Increase (decrease) in Provision	3,359	7,995
Balance at end of period	27,322	20,884
Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period	58,123	22,325
Charge-offs	(66)
Recoveries	3
Increase (decrease) in Provision	(6,369)	9,954
Balance at end of period	51,691	42,838
Construction
Allowance for loan and lease losses:
Balance at beginning of period	10,039
Recoveries	166
Increase (decrease) in Provision	347
Balance at end of period	10,552
Lease financing
Allowance for loan and lease losses:
Balance at beginning of period	3,298	424
Increase (decrease) in Provision	(101)	220
Balance at end of period	3,197	851
Consumer
Allowance for loan and lease losses:
Balance at beginning of period	64,659	34,644
Charge-offs	(6,541)	(8,597)
Recoveries	2,655	2,083
Increase (decrease) in Provision	1,692	12,334
Balance at end of period	62,465	56,039
Unallocated
Allowance for loan and lease losses:
Balance at beginning of period	208,454	139
Charge-offs	(7,668)
Recoveries	3,080
Increase (decrease) in Provision	(3,500)
Balance at end of period	200,366
Residential mortgage
Allowance for loan and lease losses:
Balance at beginning of period	40,461	29,303
Charge-offs	(98)
Recoveries	17	135
Increase (decrease) in Provision	(1,909)	3,376
Balance at end of period	38,471	30,021
Home equity
Allowance for loan and lease losses:
Balance at beginning of period	7,163	9,876
Charge-offs		(8)
Recoveries	24	122
Increase (decrease) in Provision	(519)	1,297
Balance at end of period	$ 6,668	6,556
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment
Allowance for loan and lease losses:
Balance at beginning of period		770
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Commercial Lending
Allowance for loan and lease losses:
Balance at beginning of period		(1,803)
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period		(16,105)
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period		10,559
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Lease financing
Allowance for loan and lease losses:
Balance at beginning of period		207
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Consumer
Allowance for loan and lease losses:
Balance at beginning of period		15,575
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Unallocated
Allowance for loan and lease losses:
Balance at beginning of period		(139)
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Residential mortgage
Allowance for loan and lease losses:
Balance at beginning of period		(2,793)
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Home equity
Allowance for loan and lease losses:
Balance at beginning of period		$ (4,731)