Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Adjustment to apply recent accounting pronouncements		Common Stock	Preferred Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Adjustment to apply recent accounting pronouncements		Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2018				106,375,000
Beginning balance at Dec. 31, 2018	$ 2,054,998	$ 47,257	[1]	$ 1,157	$ 0	$ 1,114,580	$ 1,192,767	$ 47,257	[1]	$ (52,512)	$ (200,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	147,617						147,617
Other comprehensive income (loss)	59,250									59,250
Common dividends declared	(43,746)						(43,746)
Repurchases of common stock (in shares)				(1,687,000)
Repurchases of common stock	(33,928)										(33,928)
Acquisitions, net of issuance costs (in shares)				4,879,000
Acquisition, net of issuance costs	101,496			$ 47		97,351					4,098
Common stock issued (in shares)				34,000
Common stock issued	687					12					675
Restricted stock activity (in shares)				380,000
Restricted stock activity	(3,833)					(13,919)					10,086
Treasury stock issued to benefit plans (in shares)				(11,000)
Treasury stock issued to benefit plans	(217)					(12)					(205)
Share-based compensation expense	10,018					10,018
Ending balance (in shares) at Sep. 30, 2019				109,970,000
Ending balance at Sep. 30, 2019	2,339,599			$ 1,204	0	1,208,030	1,343,895			6,738	(220,268)
Beginning balance (in shares) at Jun. 30, 2019				110,589,000
Beginning balance at Jun. 30, 2019	2,300,573			$ 1,204	0	1,205,396	1,304,756			(2,810)	(207,973)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	54,545						54,545
Other comprehensive income (loss)	9,548									9,548
Common dividends declared	(15,406)						(15,406)
Repurchases of common stock (in shares)				(645,000)
Repurchases of common stock	(12,738)										(12,738)
Common stock issued (in shares)				4,000
Common stock issued	82					81					1
Restricted stock activity (in shares)				27,000
Restricted stock activity	(63)					(599)					536
Treasury stock issued to benefit plans (in shares)				(5,000)
Treasury stock issued to benefit plans	(97)					(3)					(94)
Share-based compensation expense	3,155					3,155
Ending balance (in shares) at Sep. 30, 2019				109,970,000
Ending balance at Sep. 30, 2019	$ 2,339,599			$ 1,204	0	1,208,030	1,343,895			6,738	(220,268)
Beginning balance (in shares) at Dec. 31, 2019	109,972,000			109,972,000
Beginning balance at Dec. 31, 2019	$ 2,370,793	$ (26,821)	[2]	$ 1,204	0	1,211,274	1,380,612	$ (26,821)	[2]	(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)				(1,171,000)
Repurchases of common stock	(22,557)										(22,557)
Acquisitions, net of issuance costs (in shares)				4,930,000
Acquisition, net of issuance costs	71,883			$ 49		71,834
Preferred stock issued	221,047				230,500	(9,453)
Common stock issued (in shares)				49,000
Common stock issued	1,007			$ 1		327					679
Restricted stock activity (in shares)				531,000
Restricted stock activity	(3,063)					(13,311)					10,248
Treasury stock issued to benefit plans	(258)					(54)					(204)
Share-based compensation expense (in shares)				(18,000)
Share-based compensation expense	$ 11,242					11,242
Ending balance (in shares) at Sep. 30, 2020	114,293,000			114,293,000
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				114,276,000
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)				6,000
Common stock issued	77			$ 1		76					0
Restricted stock activity (in shares)				18,000
Restricted stock activity	72					(131)					203
Treasury stock issued to benefit plans (in shares)				11,000
Treasury stock issued to benefit plans	(90)					(33)					(57)
Share-based compensation expense (in shares)				(18,000)
Share-based compensation expense	$ 3,565					3,565
Ending balance (in shares) at Sep. 30, 2020	114,293,000			114,293,000
Ending balance at Sep. 30, 2020	$ 2,664,171			$ 1,254	$ 230,500	$ 1,271,859	$ 1,366,986			$ 25,749	$ (232,177)

[1] As a result of accounting guidance adopted in the first quarter of 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019.

[2] 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. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements and Other Guidance."