Loans and Allowance for Loan Losses - Activity in the Allowance for Loan Losses, by Portfolio Segment, for the Current Year (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Provision for credit loss expense	$ 26,134	$ 9,285
Balance, end of period	243,195
Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	68,244	56,694
Provision for credit loss expense	26,197	9,285
Charge-offs	(3,739)	(6,264)
Recoveries	1,116	840
Net charge-offs	(2,623)	(5,424)
Balance, end of period	243,195	60,555
Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	2,169	2,419
Provision for credit loss expense	4,698	1,206
Charge-offs	(1,379)	(1,553)
Recoveries	443	300
Net charge-offs	(936)	(1,253)
Balance, end of period	18,029	2,372
Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	22,863	20,514
Provision for credit loss expense	30,907	1,874
Charge-offs	(523)	(3,152)
Recoveries	347	158
Net charge-offs	(176)	(2,994)
Balance, end of period	76,327	19,394
Loans, Excluding Acquired Loans | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	39,161	29,838
Provision for credit loss expense	(12,158)	5,307
Charge-offs	(396)	(417)
Recoveries	101	142
Net charge-offs	(295)	(275)
Balance, end of period	141,022	34,870
Loans, Excluding Acquired Loans | Credit Card | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	4,051	3,923
Provision for credit loss expense	2,750	898
Charge-offs	(1,441)	(1,142)
Recoveries	225	240
Net charge-offs	(1,216)	(902)
Balance, end of period	7,817	$ 3,919
Impact of CECL adoption | Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	151,377
Impact of CECL adoption | Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	12,098
Impact of CECL adoption | Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	22,733
Impact of CECL adoption | Loans, Excluding Acquired Loans | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	114,314
Impact of CECL adoption | Loans, Excluding Acquired Loans | Credit Card | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	$ 2,232