Allowance for Credit Losses and Credit Quality of Loans, Allowance for Credit Losses by Portfolio Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	$ 98,500	$ 113,500	$ 110,000	$ 75,999
Charge-offs	(4,887)	(4,779)	(13,556)	(20,382)
Recoveries	2,729	2,518	7,910	7,142
Provision	(3,342)	3,261	(11,354)	51,741
Balance, end of period	93,000	114,500	93,000	114,500
Commercial Loans [Member]
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	44,191	50,386	50,942	27,156
Charge-offs	(1,492)	(624)	(2,123)	(2,353)
Recoveries	354	333	533	674
Provision	(9,875)	1,651	(16,174)	26,269
Balance, end of period	33,178	51,746	33,178	51,746
Consumer Loans [Member]
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	34,881	40,094	37,803	32,122
Charge-offs	(3,083)	(4,097)	(10,702)	(17,166)
Recoveries	2,143	2,123	6,506	6,168
Provision	7,130	442	7,464	17,438
Balance, end of period	41,071	38,562	41,071	38,562
Residential [Member]
Activity in allowance for credit losses by portfolio segment [Roll Forward]
Balance, beginning of period	19,428	23,020	21,255	16,721
Charge-offs	(312)	(58)	(731)	(863)
Recoveries	232	62	871	300
Provision	(597)	1,168	(2,644)	8,034
Balance, end of period	$ 18,751	$ 24,192	$ 18,751	$ 24,192