Loans and Allowance for Credit Losses - Activity in the Allowance for Loan Losses, by Portfolio Segment, for the Current Year (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period			$ 238,050
Provision for credit loss expense	$ (19,890)	$ 22,981	(31,396)	$ 68,030
Balance, end of period	202,508		202,508
Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	227,239	231,643	238,050	68,244
Provision for credit loss expense	(19,890)	22,313	(29,901)	75,190
Charge-offs	(8,047)	(7,403)	(14,503)	(50,298)
Recoveries	3,206	1,698	8,862	3,738
Net charge-offs	(4,841)	(5,705)	(5,641)	(46,560)
Balance, end of period	202,508	248,251	202,508	248,251
Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	3,616	12,055	5,617	2,169
Provision for credit loss expense	(122)	(2,844)	(1,737)	(3,829)
Charge-offs	(463)	(1,091)	(1,577)	(3,062)
Recoveries	408	366	1,136	1,110
Net charge-offs	(55)	(725)	(441)	(1,952)
Balance, end of period	3,439	8,486	3,439	8,486
Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	29,793	59,138	42,093	22,863
Provision for credit loss expense	(11,853)	(6,499)	(25,453)	42,808
Charge-offs	(932)	(4,327)	(2,099)	(40,537)
Recoveries	463	936	2,930	1,381
Net charge-offs	(469)	(3,391)	831	(39,156)
Balance, end of period	17,471	49,248	17,471	49,248
Loans, Excluding Acquired Loans | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	188,388	149,471	182,868	39,161
Provision for credit loss expense	(7,668)	33,479	(1,948)	31,341
Charge-offs	(5,941)	(1,153)	(8,068)	(3,373)
Recoveries	2,068	120	3,995	474
Net charge-offs	(3,873)	(1,033)	(4,073)	(2,899)
Balance, end of period	176,847	181,917	176,847	181,917
Loans, Excluding Acquired Loans | Consumer | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	5,442	10,979	7,472	4,051
Provision for credit loss expense	(247)	(1,823)	(763)	4,870
Charge-offs	(711)	(832)	(2,759)	(3,326)
Recoveries	267	276	801	773
Net charge-offs	(444)	(556)	(1,958)	(2,553)
Balance, end of period	$ 4,751	$ 8,600	$ 4,751	8,600
Cumulative Effect, Period of Adoption, Adjustment | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				151,377
Cumulative Effect, Period of Adoption, Adjustment | Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				12,098
Cumulative Effect, Period of Adoption, Adjustment | Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				22,733
Cumulative Effect, Period of Adoption, Adjustment | Loans, Excluding Acquired Loans | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				114,314
Cumulative Effect, Period of Adoption, Adjustment | Loans, Excluding Acquired Loans | Consumer | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				$ 2,232