Allowance for Credit Losses and Credit Quality of Loans, Allowance for Credit Losses by Portfolio Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	$ 105,000	$ 100,000	$ 110,000	$ 75,999
Charge-offs	(4,009)	(7,377)	(8,669)	(15,603)
Recoveries	2,725	2,037	5,181	4,624
Provision	(5,216)	18,840	(8,012)	48,480
Balance, end of period	98,500	113,500	98,500	113,500
Commercial Loans [Member]
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	50,045	42,212	50,942	27,156
Charge-offs	(389)	(709)	(631)	(1,729)
Recoveries	61	113	179	341
Provision	(5,526)	8,770	(6,299)	24,618
Balance, end of period	44,191	50,386	44,191	50,386
Consumer Loans [Member]
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	34,580	37,546	37,803	32,122
Charge-offs	(3,271)	(6,178)	(7,619)	(13,069)
Recoveries	2,288	1,810	4,363	4,045
Provision	1,284	6,916	334	16,996
Balance, end of period	34,881	40,094	34,881	40,094
Residential [Member]
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	20,375	20,242	21,255	16,721
Charge-offs	(349)	(490)	(419)	(805)
Recoveries	376	114	639	238
Provision	(974)	3,154	(2,047)	6,866
Balance, end of period	$ 19,428	$ 23,020	$ 19,428	$ 23,020