Business Segments (Operating Results and Other Key Financial Measures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	$ 1,531,571	$ 1,377,193	$ 1,467,813
(Reversal of) provision for credit losses	(35,000)	210,653	98,685
Noninterest income	285,895	235,547	222,245
Noninterest expense	796,089	716,322	747,456
INCOME BEFORE INCOME TAXES	1,056,377	685,765	843,917
Segment net income (1)	872,981	567,797	674,035
Segment assets	60,870,701	52,156,913	44,196,096
Consumer and Business Banking
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	697,101	530,829	696,551
(Reversal of) provision for credit losses	(4,998)	3,885	14,178
Noninterest income	94,125	64,115	57,238
Noninterest expense	364,635	331,750	343,001
INCOME BEFORE INCOME TAXES	431,589	259,309	396,610
Segment net income (1)	308,630	185,782	283,674
Segment assets	14,961,809	13,351,060	11,520,586
Commercial Banking
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	766,202	706,286	651,413
(Reversal of) provision for credit losses	(30,002)	206,768	84,507
Noninterest income	163,768	142,337	135,305
Noninterest expense	271,408	266,923	263,064
INCOME BEFORE INCOME TAXES	688,564	374,932	439,147
Segment net income (1)	492,271	268,476	314,321
Segment assets	28,556,706	26,958,766	25,501,534
Other
Segment Reporting Information
Net interest income before (reversal of) provision for credit losses	68,268	140,078	119,849
(Reversal of) provision for credit losses	0	0	0
Noninterest income	28,002	29,095	29,702
Noninterest expense	160,046	117,649	141,391
INCOME BEFORE INCOME TAXES	(63,776)	51,524	8,160
Segment net income (1)	72,080	113,539	76,040
Segment assets	$ 17,352,186	$ 11,847,087	$ 7,173,976