Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss		Treasury Stock
Balance Beginning (in shares) at Dec. 31, 2016			81,325,000
Beginning balance at Dec. 31, 2016		$ 1,257,080	$ 913	$ 498,937	$ 1,016,674	$ (40,910)		$ (218,534)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		22,855			22,855
Other comprehensive income		646				646
Common dividends declared ($0.09 and $0.11 per common share in 2017 and 2018, respectively)		(9,126)			(9,126)
Acquisition, net of issuance costs (in shares)			21,078,000
Acquisition, net of issuance costs		534,090	$ 210	533,322				558
Common stock issued (in shares)			2,000
Common stock issued		53		53
Restricted stock activity (in shares)			355,000
Restricted stock activity		(3,752)		(12,860)				9,108
Treasury stock issued to benefit plans (in shares)			(3,000)
Treasury stock issued to benefit plans		(78)						(78)
Share-based compensation expense		2,965		2,965
Balance Ending (in shares) at Mar. 31, 2017			102,757,000
Ending balance at Mar. 31, 2017		1,804,733	$ 1,123	1,022,417	1,030,403	(40,264)		(208,946)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to apply recent accounting pronouncements	[1]	$ 0			6,689	(6,689)	[2]
Balance Beginning (in shares) at Dec. 31, 2017		102,717,000	102,717,000
Beginning balance at Dec. 31, 2017		$ 1,864,874	$ 1,123	1,031,870	1,074,990	(33,036)		(210,073)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		33,510			33,510
Other comprehensive income		(17,806)				(17,806)
Common dividends declared ($0.09 and $0.11 per common share in 2017 and 2018, respectively)		(11,349)			(11,349)
Acquisition, net of issuance costs		0
Common stock issued (in shares)			1,000
Common stock issued		761		94				667
Restricted stock activity (in shares)			377,000
Restricted stock activity		(3,998)		(13,430)				9,432
Treasury stock issued to benefit plans (in shares)			(3,000)
Treasury stock issued to benefit plans		(72)		22				(94)
Share-based compensation expense		$ 3,367		3,367
Balance Ending (in shares) at Mar. 31, 2018		103,092,000	103,092,000
Ending balance at Mar. 31, 2018		$ 1,869,287	$ 1,123	$ 1,021,923	$ 1,103,840	$ (57,531)		$ (200,068)

[1] (1) As a result of accounting guidance adopted in the first quarter of 2018, certain reclassifications were made from accumulated other comprehensive loss to retained earnings as of January 1, 2018. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."

[2] As a result of accounting guidance adopted in the first quarter of 2018, certain reclassifications were made from accumulated other comprehensive loss to retained earnings as of January 1, 2018. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."