Operating Segments - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Average interest earning assets	$ 56,772,950	$ 57,351,808	$ 56,695,874	$ 56,362,794
Interest income	833,466	787,459	1,662,122	1,507,689
Interest expense	431,781	367,694	866,889	651,904
Net interest income	401,685	419,765	795,233	855,785
Provision (credit) for credit losses	82,070	6,050	127,270	20,487
Net interest income after provision for credit losses	319,615	413,715	667,963	835,298
Non-interest income	51,213	60,075	112,628	114,374
Non-interest expense	277,497	282,971	557,807	555,137
Internal transfer expense (income)	0	0	0	0
Income (loss) before income taxes	$ 93,331	$ 190,819	$ 222,784	$ 394,535
Return on average interest earning assets (pre-tax)	0.66%	1.33%	0.79%	1.40%
Consumer Banking | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 9,839,291	$ 9,638,329	$ 9,817,377	$ 9,557,669
Interest income	118,668	102,678	232,299	198,641
Interest expense	72,700	59,739	145,873	106,215
Net interest income	45,968	42,939	86,426	92,426
Provision (credit) for credit losses	4,820	3,492	7,892	9,936
Net interest income after provision for credit losses	41,148	39,447	78,534	82,490
Non-interest income	24,995	20,941	51,541	38,823
Non-interest expense	20,666	21,365	39,317	40,998
Internal transfer expense (income)	29,775	26,741	62,886	55,709
Income (loss) before income taxes	$ 15,702	$ 12,282	$ 27,872	$ 24,606
Return on average interest earning assets (pre-tax)	0.64%	0.51%	0.57%	0.51%
Commercial Banking | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 40,181,610	$ 39,819,608	$ 40,316,369	$ 39,105,820
Interest income	652,295	612,494	1,310,217	1,171,757
Interest expense	296,872	246,331	599,046	434,584
Net interest income	355,423	366,163	711,171	737,173
Provision (credit) for credit losses	77,291	2,840	119,493	5,846
Net interest income after provision for credit losses	278,132	363,323	591,678	731,327
Non-interest income	10,802	14,343	28,796	30,090
Non-interest expense	36,577	36,249	72,865	71,972
Internal transfer expense (income)	121,621	110,475	258,252	227,936
Income (loss) before income taxes	$ 130,736	$ 230,942	$ 289,357	$ 461,509
Return on average interest earning assets (pre-tax)	1.30%	2.32%	1.44%	2.36%
Treasury and Corporate Other | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets				$ 7,699,305
Interest income				137,291
Interest expense				111,105
Net interest income				26,186
Provision (credit) for credit losses				4,705
Net interest income after provision for credit losses				21,481
Non-interest income				45,461
Non-interest expense				442,167
Internal transfer expense (income)				(283,645)
Income (loss) before income taxes				$ (91,580)
Return on average interest earning assets (pre-tax)				(2.38%)
Treasury and Corporate Other | Treasury and Corporate Other
Segment Reporting Information [Line Items]
Average interest earning assets	$ 6,752,049	$ 7,893,871	$ 6,562,128
Interest income	62,503	72,287	119,606
Interest expense	62,209	61,624	121,970
Net interest income	294	10,663	(2,364)
Provision (credit) for credit losses	(41)	(282)	(115)
Net interest income after provision for credit losses	335	10,945	(2,249)
Non-interest income	15,416	24,791	32,291
Non-interest expense	220,254	225,357	445,625
Internal transfer expense (income)	(151,396)	(137,216)	(321,138)
Income (loss) before income taxes	$ (53,107)	$ (52,405)	$ (94,445)
Return on average interest earning assets (pre-tax)	(3.15%)	(2.66%)	(2.88%)