Business Segments - Operating Results and Other Key Financial Measures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	$ 2,312,254	$ 2,045,881	$ 1,531,571
(Reversal of) provision for credit losses	125,000	73,500	(35,000)
Noninterest income	295,264	298,666	285,895
Noninterest expense	1,022,748	859,393	796,089
INCOME BEFORE INCOME TAXES	1,459,770	1,411,654	1,056,377
Segment net income	1,161,161	1,128,083	872,981
Segment assets	69,612,884	64,112,150	60,870,701
Consumer and Business Banking
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	1,238,829	1,170,850	697,101
(Reversal of) provision for credit losses	18,422	27,197	(4,998)
Noninterest income	102,109	110,139	94,125
Noninterest expense	477,622	397,882	364,635
INCOME BEFORE INCOME TAXES	844,894	855,910	431,589
Segment net income	596,366	608,120	308,630
Segment assets	19,510,836	17,385,804	14,961,809
Commercial Banking
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	992,519	892,386	766,202
(Reversal of) provision for credit losses	106,578	46,303	(30,002)
Noninterest income	174,465	179,248	163,768
Noninterest expense	382,865	314,185	275,649
INCOME BEFORE INCOME TAXES	677,541	711,146	684,323
Segment net income	478,418	507,467	489,233
Segment assets	35,095,237	33,042,785	28,556,706
Other
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	80,906	(17,355)	68,268
(Reversal of) provision for credit losses	0	0	0
Noninterest income	18,690	9,279	28,002
Noninterest expense	162,261	147,326	155,805
INCOME BEFORE INCOME TAXES	(62,665)	(155,402)	(59,535)
Segment net income	86,377	12,496	75,118
Segment assets	$ 15,006,811	$ 13,683,561	$ 17,352,186