Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment		Common Stock	Preferred Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period Of Adoption, Adjustment		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	93,072						93,072
Other comprehensive income (loss)	49,702									49,702
Common dividends declared	(28,340)						(28,340)
Repurchases of common stock (in shares)				(1,042,000)
Repurchases of common stock	(21,190)										(21,190)
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)				30,000
Common stock issued	605					(69)					674
Restricted stock activity (in shares)				353,000
Restricted stock activity	(3,770)					(13,320)					9,550
Treasury stock issued to benefit plans (in shares)				(6,000)
Treasury stock issued to benefit plans	(120)					(9)					(111)
Share-based compensation expense	6,863					6,863
Ending balance (in shares) at Jun. 30, 2019				110,589,000
Ending balance at Jun. 30, 2019	2,300,573			$ 1,204	0	1,205,396	1,304,756			(2,810)	(207,973)
Beginning balance (in shares) at Mar. 31, 2019				106,900,000
Beginning balance at Mar. 31, 2019	2,159,471			$ 1,157	0	1,103,991	1,273,245			(32,159)	(186,763)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	47,014						47,014
Other comprehensive income (loss)	29,349									29,349
Common dividends declared	(15,503)						(15,503)
Repurchases of common stock (in shares)				(1,042,000)
Repurchases of common stock	(21,190)										(21,190)
Acquisitions, net of issuance costs (in shares)				4,729,000
Acquisition, net of issuance costs	98,212			$ 47		98,165					0
Common stock issued (in shares)				3,000
Common stock issued	68					68					0
Restricted stock activity (in shares)				1,000
Restricted stock activity	5					(7)					12
Treasury stock issued to benefit plans (in shares)				(2,000)
Treasury stock issued to benefit plans	(37)					(5)					(32)
Share-based compensation expense	3,184					3,184
Ending balance (in shares) at Jun. 30, 2019				110,589,000
Ending balance at Jun. 30, 2019	$ 2,300,573			$ 1,204	0	1,205,396	1,304,756			(2,810)	(207,973)
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	38,670						38,670
Other comprehensive income (loss)	30,681									30,681
Preferred dividends	(1,037)						(1,037)
Common dividends declared	(32,017)						(32,017)
Preferred stock issued	221,312				230,500	(9,188)
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
Common stock issued (in shares)				43,000
Common stock issued	930			$ 0		251					679
Restricted stock activity (in shares)				513,000
Restricted stock activity	(3,135)					(13,180)					10,045
Treasury stock issued to benefit plans (in shares)				(11,000)
Treasury stock issued to benefit plans	(168)					(21)					(147)
Share-based compensation expense	$ 7,677					7,677
Ending balance (in shares) at Jun. 30, 2020	114,276,000			114,276,000
Ending balance at Jun. 30, 2020	$ 2,656,211			$ 1,253	230,500	1,268,647	1,359,407			28,727	(232,323)
Beginning balance (in shares) at Mar. 31, 2020				114,213,000
Beginning balance at Mar. 31, 2020	2,435,707			$ 1,253	0	1,274,935	1,357,395			35,323	(233,199)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	19,064						19,064
Other comprehensive income (loss)	(6,596)									(6,596)
Preferred dividends	(1,037)						(1,037)
Common dividends declared	(16,015)						(16,015)
Preferred stock issued	221,312				230,500	(9,188)
Common stock issued (in shares)				6,000
Common stock issued	79					79					0
Restricted stock activity (in shares)				64,000
Restricted stock activity	31					(912)					943
Treasury stock issued to benefit plans (in shares)				(7,000)
Treasury stock issued to benefit plans	(89)					(22)					(67)
Share-based compensation expense	$ 3,755					3,755
Ending balance (in shares) at Jun. 30, 2020	114,276,000			114,276,000
Ending balance at Jun. 30, 2020	$ 2,656,211			$ 1,253	$ 230,500	$ 1,268,647	$ 1,359,407			$ 28,727	$ (232,323)

[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."