Segment Reporting (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) employee	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) employee segment	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) employee
Segment Reporting [Abstract]
Number of reportable segments | segment			3
Income Statement Related Disclosures [Abstract]
Net interest income	$ 381,860	$ 376,566	$ 755,716	$ 749,826
Non-interest revenue	107,087	173,484	218,043	277,341
Non-interest expense	270,531	284,141	537,665	560,421
Pre-provision net revenue	218,416	265,909	436,094	466,746
Balance Sheet Related Disclosures [Abstract]
Loans, net of deferred fees and costs	38,236,018		38,236,018		$ 38,252,984
Total deposits	$ 47,171,962		$ 47,171,962		$ 46,691,571
Total full-time equivalent employees | employee	4,983		4,983		5,134
Operating Segments | Community Banking
Income Statement Related Disclosures [Abstract]
Net interest income	$ 202,881	219,097	$ 409,123	415,601
Non-interest revenue	32,212	23,747	61,966	54,071
Non-interest expense	69,120	74,764	137,178	148,737
Pre-provision net revenue	165,973	168,080	333,911	320,935
Balance Sheet Related Disclosures [Abstract]
Loans, net of deferred fees and costs	10,730,544		10,730,544		$ 11,171,013
Total deposits	$ 31,317,490		$ 31,317,490		$ 29,141,242
Total full-time equivalent employees | employee	2,114		2,114		2,199
Operating Segments | Wholesale Banking
Income Statement Related Disclosures [Abstract]
Net interest income	$ 136,126	145,016	$ 270,200	268,186
Non-interest revenue	7,000	5,682	14,319	15,009
Non-interest expense	21,290	22,934	42,014	43,647
Pre-provision net revenue	121,836	127,764	242,505	239,548
Balance Sheet Related Disclosures [Abstract]
Loans, net of deferred fees and costs	19,369,933		19,369,933		$ 18,810,729
Total deposits	$ 10,983,120		$ 10,983,120		$ 11,958,105
Total full-time equivalent employees | employee	288		288		285
Operating Segments | Financial Management Services
Income Statement Related Disclosures [Abstract]
Net interest income	$ 18,935	20,069	$ 39,930	37,453
Non-interest revenue	52,345	52,976	110,928	100,360
Non-interest expense	46,773	48,394	94,447	91,785
Pre-provision net revenue	24,507	24,651	56,411	46,028
Balance Sheet Related Disclosures [Abstract]
Loans, net of deferred fees and costs	5,078,318		5,078,318		$ 5,370,790
Total deposits	$ 737,202		$ 737,202		$ 739,200
Total full-time equivalent employees | employee	809		809		832
Treasury and Corporate Other
Income Statement Related Disclosures [Abstract]
Net interest income	$ 23,918	(7,616)	$ 36,463	28,586
Non-interest revenue	15,530	91,079	30,830	107,901
Non-interest expense	133,348	138,049	264,026	276,252
Pre-provision net revenue	(93,900)	$ (54,586)	(196,733)	$ (139,765)
Balance Sheet Related Disclosures [Abstract]
Loans, net of deferred fees and costs	3,057,223		3,057,223		$ 2,900,452
Total deposits	$ 4,134,150		$ 4,134,150		$ 4,853,024
Total full-time equivalent employees | employee	1,772		1,772		1,818