Parent Company Information (Components of Condensed Cash Flow The Parent Company) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net income	$ 408,864	$ 220,621	$ 382,723
Adjustments to reconcile net income to net cash provided by operating activities:
Net cash provided by operating activities	688,592	380,549	303,850
Investing activities:
Alternative investments (capital call), net of distributions	(11,361)	(12,244)	(6,065)
Net cash provided by (used for) investing activities	(2,405,089)	(2,288,609)	(2,549,756)
Financing activities:
Cash dividends paid to common shareholders	(144,807)	(144,965)	(140,783)
Cash dividends paid to preferred shareholders	(7,875)	(7,875)	(7,875)
Exercise of stock options	3,492	240	619
Common stock repurchased and acquired from stock compensation plan activity	0	(76,556)	(13,003)
Net cash (used for) provided by financing activities	1,914,963	1,913,269	2,174,302
Net (decrease) increase in cash and cash equivalents	198,466	5,209	(71,604)
Cash and cash equivalents at beginning of year	263,104	257,895	329,499
Cash and cash equivalents at end of year	461,570	263,104	257,895
Parent Company [Member]
Operating activities:
Net income	408,864	220,621	382,723
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	(238,254)	(222,528)	(43,787)
Other, net	3,562	29,697	23,681
Net cash provided by operating activities	174,172	27,790	362,617
Investing activities:
Alternative investments (capital call), net of distributions	(6,304)	(3,751)	(1,850)
Investment in subsidiaries	0	0	(296,000)
Net cash provided by (used for) investing activities	(6,304)	(3,751)	(297,850)
Financing activities:
Issuance of long-term debt	0	0	296,358
Cash dividends paid to common shareholders	145,223	144,967	140,783
Cash dividends paid to preferred shareholders	7,875	7,875	7,875
Exercise of stock options	3,492	240	619
Common stock repurchased and acquired from stock compensation plan activity	4,384	80,062	19,619
Net cash (used for) provided by financing activities	(153,990)	(232,664)	128,700
Net (decrease) increase in cash and cash equivalents	13,878	(208,625)	193,467
Cash and cash equivalents at beginning of year	302,315	510,940	317,473
Cash and cash equivalents at end of year	$ 316,193	$ 302,315	$ 510,940