Business Segments - Operating Results and Other Key Financial Measures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment Reporting Information
Net interest income before provision for credit losses	$ 599,861	$ 415,613
Provision for credit losses	20,000	8,000
Noninterest income (loss)	59,978	79,743
Noninterest expense	218,447	189,450
INCOME BEFORE INCOME TAXES	421,392	297,906
Segment net income	322,439	237,652
Segment assets	67,244,898	62,241,456	$ 64,112,150
Consumer and Business Banking
Segment Reporting Information
Net interest income before provision for credit losses	304,242	213,214
Provision for credit losses	15,012	3,104
Noninterest income (loss)	26,002	25,199
Noninterest expense	113,823	96,095
INCOME BEFORE INCOME TAXES	201,409	139,214
Segment net income	142,247	99,164
Segment assets	17,880,525	15,338,579
Commercial Banking
Segment Reporting Information
Net interest income before provision for credit losses	236,723	208,077
Provision for credit losses	4,988	4,896
Noninterest income (loss)	43,599	49,077
Noninterest expense	87,248	73,395
INCOME BEFORE INCOME TAXES	188,086	178,863
Segment net income	134,457	127,507
Segment assets	33,647,465	30,199,416
Other
Segment Reporting Information
Net interest income before provision for credit losses	58,896	(5,678)
Provision for credit losses	0	0
Noninterest income (loss)	(9,623)	5,467
Noninterest expense	17,376	19,960
INCOME BEFORE INCOME TAXES	31,897	(20,171)
Segment net income	45,735	10,981
Segment assets	$ 15,716,908	$ 16,703,461