Allowance for Credit Losses - Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for loan and lease losses:
Balance at beginning of period	$ 130,530	$ 141,718	$ 137,253
Adoption of ASU 2016-13		770
Charge-offs	(47,563)	(35,987)	(27,573)
Recoveries	16,702	10,999	9,858
Increase (decrease) in Provision	108,015	13,800	22,180
Balance at end of period	208,454	130,530	141,718
Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period	28,975	34,501	34,006
Adoption of ASU 2016-13		(16,105)
Charge-offs	(15,572)	(2,718)	(778)
Recoveries	5,005	410	232
Increase (decrease) in Provision	22,408	(3,218)	1,041
Balance at end of period	24,711	28,975	34,501
Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period	22,325	19,725	18,044
Adoption of ASU 2016-13		10,559
Charge-offs	(2,753)
Recoveries	615	263	216
Increase (decrease) in Provision	27,377	2,337	1,465
Balance at end of period	58,123	22,325	19,725
Construction
Allowance for loan and lease losses:
Balance at beginning of period	4,844	5,813	6,817
Adoption of ASU 2016-13		(1,803)
Charge-offs	(379)
Recoveries	200
Increase (decrease) in Provision	7,177	(969)	(1,004)
Balance at end of period	10,039	4,844	5,813
Lease financing
Allowance for loan and lease losses:
Balance at beginning of period	424	432	611
Adoption of ASU 2016-13		207
Charge-offs		(24)
Increase (decrease) in Provision	2,667	16	(179)
Balance at end of period	3,298	424	432
Residential
Allowance for loan and lease losses:
Balance at beginning of period	39,179	44,906	42,852
Charge-offs		(438)	(165)
Recoveries		967	940
Increase (decrease) in Provision		(6,256)	1,279
Balance at end of period		39,179	44,906
Consumer
Allowance for loan and lease losses:
Balance at beginning of period	34,644	35,813	31,249
Adoption of ASU 2016-13		15,575
Charge-offs	(28,791)	(32,807)	(26,630)
Recoveries	10,499	9,359	8,470
Increase (decrease) in Provision	32,732	22,279	22,724
Balance at end of period	64,659	34,644	35,813
Unallocated
Allowance for loan and lease losses:
Balance at beginning of period	139	528	3,674
Adoption of ASU 2016-13		(139)
Increase (decrease) in Provision		(389)	(3,146)
Balance at end of period		139	$ 528
Residential mortgage
Allowance for loan and lease losses:
Balance at beginning of period	29,303
Adoption of ASU 2016-13		(2,793)
Charge-offs	(14)
Recoveries	216
Increase (decrease) in Provision	13,749
Balance at end of period	40,461	29,303
Home equity
Allowance for loan and lease losses:
Balance at beginning of period	9,876
Adoption of ASU 2016-13		(4,731)
Charge-offs	(54)
Recoveries	167
Increase (decrease) in Provision	1,905
Balance at end of period	$ 7,163	$ 9,876