Business Segments - Operating Results and Other Key Financial Measures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information
Net interest income (loss) before provision for credit losses	$ 566,746	$ 472,952	$ 1,166,607	$ 888,565
Provision for credit losses	26,000	13,500	46,000	21,500
Noninterest income	78,631	78,444	138,609	158,187
Noninterest expense	261,789	196,860	480,236	386,310
INCOME BEFORE INCOME TAXES	357,588	341,036	778,980	638,942
Segment net income (loss)	312,031	258,329	634,470	495,981
Segment assets	68,532,681	62,394,283	68,532,681	62,394,283	$ 64,112,150
Consumer and Business Banking
Segment Reporting Information
Net interest income (loss) before provision for credit losses	307,522	284,373	611,764	497,587
Provision for credit losses	5,524	2,898	20,536	6,002
Noninterest income	27,120	28,384	53,122	53,583
Noninterest expense	107,027	94,295	220,850	190,390
INCOME BEFORE INCOME TAXES	222,091	215,564	423,500	354,778
Segment net income (loss)	156,853	153,549	299,100	252,713
Segment assets	18,411,209	16,472,373	18,411,209	16,472,373
Commercial Banking
Segment Reporting Information
Net interest income (loss) before provision for credit losses	263,040	230,964	499,763	439,041
Provision for credit losses	20,476	10,602	25,464	15,498
Noninterest income	42,538	48,032	86,137	97,109
Noninterest expense	88,333	81,023	175,581	154,418
INCOME BEFORE INCOME TAXES	196,769	187,371	384,855	366,234
Segment net income (loss)	139,030	133,861	273,487	261,368
Segment assets	33,754,957	32,256,044	33,754,957	32,256,044
Other
Segment Reporting Information
Net interest income (loss) before provision for credit losses	(3,816)	(42,385)	55,080	(48,063)
Provision for credit losses	0	0	0	0
Noninterest income	8,973	2,028	(650)	7,495
Noninterest expense	66,429	21,542	83,805	41,502
INCOME BEFORE INCOME TAXES	(61,272)	(61,899)	(29,375)	(82,070)
Segment net income (loss)	16,148	(29,081)	61,883	(18,100)
Segment assets	$ 16,366,515	$ 13,665,866	$ 16,366,515	$ 13,665,866