Consolidated Statements of Changes in Stockholders’ Equity - USD ($) shares in Thousands, $ in Thousands		Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2015			77,952
Beginning balance at Dec. 31, 2015		$ 1,146,268	$ 882	$ 446,672	$ 953,516	$ (28,389)	$ (226,413)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		92,349			92,349
Other comprehensive (loss) income		(12,521)				(12,521)
Common dividends declared ($0.36, $0.39 and $0.45)		(29,191)			(29,191)
Acquisition, net of issuance costs (in shares)			3,042
Acquisition, net of issuance costs		54,896	$ 31	54,865
Common stock issued (in shares)			13
Common stock issued		227		227
Restricted stock activity (in shares)			326
Restricted stock activity		(2,673)		(10,685)			8,012
Treasury stock issued to benefit plans (in shares)			(8)
Treasury stock issued to benefit plans		(154)		(21)			(133)
Share-based compensation expense		7,879		7,879
Ending balance (in shares) at Dec. 31, 2016			81,325
Ending 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		98,387			98,387
Other comprehensive (loss) income		7,874				7,874
Common dividends declared ($0.36, $0.39 and $0.45)		(40,071)			(40,071)
Acquisition, net of issuance costs (in shares)			21,078
Acquisition, net of issuance costs		534,090	$ 210	533,322			558
Common stock issued (in shares)			9
Common stock issued		240		240
Restricted stock activity (in shares)			317
Restricted stock activity		(3,659)		(11,855)			8,196
Treasury stock issued to benefit plans (in shares)			(12)
Treasury stock issued to benefit plans		(290)		3			(293)
Share-based compensation expense		$ 11,223		11,223
Ending balance (in shares) at Dec. 31, 2017		102,717	102,717
Ending 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]
Adjustments to apply recent accounting pronouncements	[1]	0			6,689	(6,689)
Net income		157,870			157,870
Other comprehensive (loss) income		(12,787)				(12,787)
Common dividends declared ($0.36, $0.39 and $0.45)		(46,782)			(46,782)
Acquisition, net of issuance costs (in shares)			3,311
Acquisition, net of issuance costs		83,303	$ 33	83,270
Common stock issued (in shares)			39
Common stock issued		961	$ 1	293			667
Restricted stock activity (in shares)			311
Restricted stock activity		(4,421)		(12,983)			8,562
Treasury stock issued to benefit plans (in shares)			(3)
Treasury stock issued to benefit plans		(82)		68			(150)
Share-based compensation expense		$ 12,062		12,062
Ending balance (in shares) at Dec. 31, 2018		106,375	106,375
Ending balance at Dec. 31, 2018		$ 2,054,998	$ 1,157	$ 1,114,580	$ 1,192,767	(52,512)	$ (200,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to apply recent accounting pronouncements	[1]					$ (6,689)

[1] As a result of accounting guidance adopted in 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."