Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	$ 104,779	$ 95,854	$ 103,419	$ 96,729
Charge-offs	(11,424)	(11,309)	(22,201)	(28,394)
Recoveries	2,083	1,532	3,776	2,561
Net charge-offs	(9,341)	(9,777)	(18,425)	(25,833)
Provision for loan losses and other	11,491	11,614	21,935	26,795
Ending balance	106,929	97,691	106,929	97,691
Reserve for Unfunded Commitments
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	1,200	1,000	1,200	1,000
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net charge-offs	0	0	0	0
Provision for loan losses and other	0	0	0	0
Ending balance	1,200	1,000	1,200	1,000
Commercial, Industrial, and Agricultural
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	64,685	57,200	63,276	55,791
Charge-offs	(6,516)	(8,662)	(12,967)	(23,332)
Recoveries	1,258	753	2,559	1,291
Net charge-offs	(5,258)	(7,909)	(10,408)	(22,041)
Provision for loan losses and other	6,937	10,752	13,496	26,293
Ending balance	66,364	60,043	66,364	60,043
Commercial Real Estate
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance			17,471
Ending balance	16,513		16,513
Commercial Real Estate | Office, Retail, and Industrial
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	7,679	10,607	7,900	10,996
Charge-offs	(1,605)	(305)	(2,233)	(766)
Recoveries	151	26	161	123
Net charge-offs	(1,454)	(279)	(2,072)	(643)
Provision for loan losses and other	1,270	(1,266)	1,667	(1,291)
Ending balance	7,495	9,062	7,495	9,062
Commercial Real Estate | Multi-family
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	2,216	2,592	2,464	2,534
Charge-offs	0	(4)	(340)	(4)
Recoveries	0	0	1	0
Net charge-offs	0	(4)	(339)	(4)
Provision for loan losses and other	(57)	(413)	34	(355)
Ending balance	2,159	2,175	2,159	2,175
Commercial Real Estate | Construction
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	2,131	1,972	2,173	3,481
Charge-offs	0	0	(6)	0
Recoveries	10	8	16	21
Net charge-offs	10	8	10	21
Provision for loan losses and other	(279)	144	(321)	(1,378)
Ending balance	1,862	2,124	1,862	2,124
Commercial Real Estate | Other Commercial Real Estate
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	4,930	5,291	4,934	6,381
Charge-offs	(329)	(1)	(539)	(70)
Recoveries	45	359	66	398
Net charge-offs	(284)	358	(473)	328
Provision for loan losses and other	351	(1,018)	536	(2,078)
Ending balance	4,997	4,631	4,997	4,631
Consumer
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance			21,472
Ending balance	22,852		22,852
Consumer | Consumer
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	21,938	17,192	21,472	16,546
Charge-offs	(2,974)	(2,337)	(6,116)	(4,222)
Recoveries	619	386	973	728
Net charge-offs	(2,355)	(1,951)	(5,143)	(3,494)
Provision for loan losses and other	3,269	3,415	6,523	5,604
Ending balance	$ 22,852	$ 18,656	$ 22,852	$ 18,656