Business Segments - Operating Results and Other Key Financial Measures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information
Net interest income (loss) before provision for credit losses	$ 570,813	$ 551,809	$ 1,737,420	$ 1,440,374
Provision for credit losses	42,000	27,000	88,000	48,500
Noninterest income (loss)	76,752	75,552	215,361	233,739
Noninterest expense	252,014	215,973	732,250	602,283
INCOME BEFORE INCOME TAXES	353,551	384,388	1,132,531	1,023,330
Segment net income (loss)	287,738	295,339	922,208	791,320
Segment assets	68,289,458	62,576,061	68,289,458	62,576,061	$ 64,112,150
Consumer and Business Banking
Segment Reporting Information
Net interest income (loss) before provision for credit losses	315,409	326,411	927,173	823,998
Provision for credit losses	1,633	8,974	22,169	14,976
Noninterest income (loss)	25,132	30,819	78,254	84,402
Noninterest expense	106,626	104,005	327,476	294,395
INCOME BEFORE INCOME TAXES	232,282	244,251	655,782	599,029
Segment net income (loss)	164,051	173,982	463,151	426,695
Segment assets	18,935,452	17,002,000	18,935,452	17,002,000
Commercial Banking
Segment Reporting Information
Net interest income (loss) before provision for credit losses	242,345	222,996	742,108	662,037
Provision for credit losses	40,367	18,026	65,831	33,524
Noninterest income (loss)	43,672	48,641	129,809	145,750
Noninterest expense	87,556	81,386	263,137	235,804
INCOME BEFORE INCOME TAXES	158,094	172,225	542,949	538,459
Segment net income (loss)	110,182	122,869	383,669	384,237
Segment assets	34,438,787	32,836,381	34,438,787	32,836,381
Other
Segment Reporting Information
Net interest income (loss) before provision for credit losses	13,059	2,402	68,139	(45,661)
Provision for credit losses	0	0	0	0
Noninterest income (loss)	7,948	(3,908)	7,298	3,587
Noninterest expense	57,832	30,582	141,637	72,084
INCOME BEFORE INCOME TAXES	(36,825)	(32,088)	(66,200)	(114,158)
Segment net income (loss)	13,505	(1,512)	75,388	(19,612)
Segment assets	$ 14,915,219	$ 12,737,680	$ 14,915,219	$ 12,737,680