Operating Segments - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Average interest earning assets	$ 58,623,153	$ 57,651,650	$ 57,695,831	$ 57,016,790
Interest income	826,923	860,549	2,416,687	2,522,671
Interest expense	380,699	450,051	1,117,950	1,316,940
Net interest income	446,224	410,498	1,298,737	1,205,731
Provision for credit losses	19,171	75,024	119,631	202,294
Net interest income after provision for credit losses	427,053	335,474	1,179,106	1,003,437
Non-interest income	64,887	60,671	185,785	173,299
Salary and employee benefits expense	146,820	138,832	434,860	421,478
Net occupancy expense	24,865	26,973	76,236	75,548
Technology, furniture and equipment expense	30,708	28,962	91,271	99,627
FDIC insurance assessment	8,357	14,792	33,416	47,474
Professional and legal fees	24,261	14,118	59,901	48,521
Loss on extinguishment of debt	0	0	(922)	0
Other segment items	46,974	45,794	146,119	134,630
Non-interest expense	281,985	269,471	842,725	827,278
Income Before Income Taxes	$ 209,955	$ 126,674	$ 522,166	$ 349,458
Return on average interest earning assets (pre-tax)	1.43%	0.88%	1.21%	0.82%
Net interest margin	3.04%	2.85%	3.00%	2.82%
Treasury and Corporate Other
Segment Reporting Information [Line Items]
Average interest earning assets	$ 9,352,300	$ 7,524,687	$ 8,707,438	$ 6,885,322
Interest income	94,958	77,710	263,325	197,315
Interest expense	60,760	58,697	168,720	159,033
Net interest income	34,198	19,013	94,605	38,282
Provision for credit losses	0	(14)	(10)	(129)
Net interest income after provision for credit losses	34,198	19,027	94,615	38,411
Non-interest income	4,344	7,533	14,695	15,804
Salary and employee benefits expense	18,777	13,138	40,386	36,071
Net occupancy expense	3,956	3,454	11,433	8,989
Technology, furniture and equipment expense	4,458	3,466	12,196	11,000
FDIC insurance assessment	(3,817)	0	(3,817)	8,757
Professional and legal fees	3,109	1,341	7,372	4,202
Loss on extinguishment of debt			(922)
Other segment items	17,703	20,339	57,761	58,796
Non-interest expense	44,186	41,738	126,253	127,815
Income Before Income Taxes	$ (5,644)	$ (15,178)	$ (16,943)	$ (73,600)
Return on average interest earning assets (pre-tax)	(0.24%)	(0.81%)	(0.26%)	(1.43%)
Net interest margin	1.46%	1.01%	1.45%	0.74%
Consumer Banking | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 10,828,927	$ 9,918,669	$ 10,565,249	$ 9,848,502
Interest income	134,090	123,252	387,169	355,551
Interest expense	70,362	77,409	204,719	227,475
Net interest income	63,728	45,843	182,450	128,076
Provision for credit losses	3,353	6,007	(4,663)	13,899
Net interest income after provision for credit losses	60,375	39,836	187,113	114,177
Non-interest income	37,878	35,940	104,424	100,673
Salary and employee benefits expense	34,885	30,798	99,153	89,231
Net occupancy expense	4,668	4,715	14,145	13,245
Technology, furniture and equipment expense	7,142	5,898	19,645	19,024
FDIC insurance assessment	2,680	2,922	8,030	7,606
Professional and legal fees	3,739	2,380	9,982	7,585
Loss on extinguishment of debt			0
Other segment items	14,285	13,628	40,592	39,159
Non-interest expense	67,399	60,341	191,547	175,850
Income Before Income Taxes	$ 30,854	$ 15,435	$ 99,990	$ 39,000
Return on average interest earning assets (pre-tax)	1.14%	0.62%	1.26%	0.53%
Net interest margin	2.35%	1.85%	2.31%	1.73%
Commercial Banking | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 38,441,926	$ 40,208,294	$ 38,423,144	$ 40,282,966
Interest income	597,875	659,587	1,766,193	1,969,805
Interest expense	249,577	313,945	744,511	930,432
Net interest income	348,298	345,642	1,021,682	1,039,373
Provision for credit losses	15,818	69,031	124,304	188,524
Net interest income after provision for credit losses	332,480	276,611	897,378	850,849
Non-interest income	22,665	17,198	66,666	56,822
Salary and employee benefits expense	93,158	94,896	295,321	296,176
Net occupancy expense	16,241	18,804	50,658	53,314
Technology, furniture and equipment expense	19,108	19,598	59,430	69,603
FDIC insurance assessment	9,494	11,870	29,203	31,111
Professional and legal fees	17,413	10,397	42,547	36,734
Loss on extinguishment of debt			0
Other segment items	14,986	11,827	47,766	36,675
Non-interest expense	170,400	167,392	524,925	523,613
Income Before Income Taxes	$ 184,745	$ 126,417	$ 439,119	$ 384,058
Return on average interest earning assets (pre-tax)	1.92%	1.26%	1.52%	1.27%
Net interest margin	3.62%	3.44%	3.55%	3.44%