Consolidated Statements of Changes In Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Adjustment to apply recent accounting pronouncements	[1]	Common Shares Outstanding	Preferred Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Adjustment to apply recent accounting pronouncements	[1]	Total Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2019				109,972
Beginning balance at Dec. 31, 2019	$ 2,370,793	$ (26,821)		$ 1,204	$ 0	$ 1,211,274	$ 1,380,612	$ (26,821)		$ (1,954)	$ (220,343)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	66,293						66,293
Other comprehensive income (loss)	27,703									27,703
Preferred dividends	(5,070)						(5,070)
Common dividends declared	(48,028)						(48,028)
Repurchases of common stock (in shares)				(1,171)
Repurchases of common stock	(22,557)										(22,557)
Acquisitions, net of issuance costs (in shares)				4,930
Acquisition, net of issuance costs	71,883			$ 49		71,834
Preferred stock issued	221,047				230,500	(9,453)
Common stock issued (in shares)				49
Common stock issued	1,007			$ 1		327					679
Restricted stock activity (in shares)				531
Restricted stock activity	(3,063)					(13,311)					10,248
Treasury stock issued to benefit plans	(258)					(54)					(204)
Share-based compensation expense (in shares)				(18)
Share-based compensation expense	11,242					11,242
Ending balance (in shares) at Sep. 30, 2020				114,293
Ending balance at Sep. 30, 2020	2,664,171			$ 1,254	230,500	1,271,859	1,366,986			25,749	(232,177)
Beginning balance (in shares) at Jun. 30, 2020				114,276
Beginning balance at Jun. 30, 2020	2,656,211			$ 1,253	230,500	1,268,647	1,359,407			28,727	(232,323)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	27,623						27,623
Other comprehensive income (loss)	(2,978)									(2,978)
Preferred dividends	(4,033)						(4,033)
Common dividends declared	(16,011)						(16,011)
Preferred stock issued	(265)					(265)
Common stock issued (in shares)				6
Common stock issued	77			$ 1		76
Restricted stock activity (in shares)				18
Restricted stock activity	72					(131)					203
Treasury stock issued to benefit plans (in shares)				11
Treasury stock issued to benefit plans	(90)					(33)					(57)
Share-based compensation expense (in shares)				(18)
Share-based compensation expense	3,565					3,565
Ending balance (in shares) at Sep. 30, 2020				114,293
Ending balance at Sep. 30, 2020	$ 2,664,171			$ 1,254	230,500	1,271,859	1,366,986			25,749	(232,177)
Beginning balance (in shares) at Dec. 31, 2020	114,296			114,296
Beginning balance at Dec. 31, 2020	$ 2,690,006			$ 1,254	230,500	1,275,492	1,388,525			26,379	(232,144)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	151,007						151,007
Other comprehensive income (loss)	(51,760)									(51,760)
Preferred dividends	(12,101)						(12,101)
Common dividends declared	(47,950)						(47,950)
Repurchases of common stock (in shares)				(715)
Repurchases of common stock	(14,929)										(14,929)
Acquisition, net of issuance costs	0
Common stock issued (in shares)				73
Common stock issued	1,173			$ 0		129					1,044
Restricted stock activity (in shares)				500
Restricted stock activity	(4,031)					(14,047)					10,016
Treasury stock issued to benefit plans (in shares)				13
Treasury stock issued to benefit plans	269					35					234
Share-based compensation expense	$ 11,539					11,539
Ending balance (in shares) at Sep. 30, 2021	114,167			114,167
Ending balance at Sep. 30, 2021	$ 2,723,223			$ 1,254	230,500	1,273,148	1,479,481			(25,381)	(235,779)
Beginning balance (in shares) at Jun. 30, 2021				114,177
Beginning balance at Jun. 30, 2021	2,704,148			$ 1,254	230,500	1,269,192	1,444,625			(5,941)	(235,482)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	54,863						54,863
Other comprehensive income (loss)	(19,440)									(19,440)
Preferred dividends	(4,033)						(4,033)
Common dividends declared	(15,974)						(15,974)
Common stock issued (in shares)				4
Common stock issued	74					73					1
Restricted stock activity (in shares)				(26)
Restricted stock activity	(29)					487					(516)
Treasury stock issued to benefit plans (in shares)				12
Treasury stock issued to benefit plans	232					14					218
Share-based compensation expense	$ 3,382					3,382
Ending balance (in shares) at Sep. 30, 2021	114,167			114,167
Ending balance at Sep. 30, 2021	$ 2,723,223			$ 1,254	$ 230,500	$ 1,273,148	$ 1,479,481			$ (25,381)	$ (235,779)

[1] As a result of accounting guidance adopted in the first quarter of 2020, a portion of the increase in allowance for credit losses, net of tax, was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2020.