UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Earnings
Balance at beginning of period at Dec. 31, 2017	$ 1,188,202	$ 565	$ 686,962	$ (172,407)	$ 673,082
Balance beginning of period (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Net income	(12,631)				(12,631)
Other comprehensive income	(16,746)			(16,746)
Stock-based compensation	3,077		3,077
Issuance of restricted shares, net of shares remitted and tax withholdings	(548)	$ 0	(548)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		24
Repurchases of common stock	(14,264)	$ (3)	(14,261)
Repurchases of common stock (in shares)		(280)
Balance at end of period at Mar. 31, 2018	1,145,526	$ 562	675,230	(189,153)	658,887
Balance ending of period (in shares) at Mar. 31, 2018		56,245
Balance at beginning of period at Dec. 31, 2017	1,188,202	$ 565	686,962	(172,407)	673,082
Balance beginning of period (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Net income	18,116
Other comprehensive income	(21,688)
Repurchases of common stock	$ (26,500)
Repurchases of common stock (in shares)	(500)
Balance at end of period at Jun. 30, 2018	$ 1,161,048	$ 561	664,948	(194,095)	689,634
Balance ending of period (in shares) at Jun. 30, 2018		56,087
Balance at beginning of period at Mar. 31, 2018	1,145,526	$ 562	675,230	(189,153)	658,887
Balance beginning of period (in shares) at Mar. 31, 2018		56,245
Increase (Decrease) in Stockholders' Equity
Net income	30,747				30,747
Other comprehensive income	(4,942)			(4,942)
Stock-based compensation	3,562		3,562
Issuance of restricted shares, net of shares remitted and tax withholdings	(1,627)	$ 1	(1,628)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		94
Repurchases of common stock	$ (12,218)	$ (2)	(12,216)
Repurchases of common stock (in shares)	(200)	(252)
Balance at end of period at Jun. 30, 2018	$ 1,161,048	$ 561	664,948	(194,095)	689,634
Balance ending of period (in shares) at Jun. 30, 2018		56,087
Balance at beginning of period at Dec. 31, 2018	1,169,756	$ 558	655,415	(223,371)	737,154
Balance beginning of period (in shares) at Dec. 31, 2018		55,847
Increase (Decrease) in Stockholders' Equity
Net income	976				976
Other comprehensive income	4,024			4,024
Stock-based compensation	5,809		5,809
Issuance of restricted shares, net of shares remitted and tax withholdings	(2,276)	$ 1	(2,277)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		78
Repurchases of common stock	(6,324)	$ (1)	(6,323)
Repurchases of common stock (in shares)		(97)
Balance at end of period at Mar. 31, 2019	1,171,965	$ 558	652,624	(219,347)	738,130
Balance ending of period (in shares) at Mar. 31, 2019		55,828
Balance at beginning of period at Dec. 31, 2018	1,169,756	$ 558	655,415	(223,371)	737,154
Balance beginning of period (in shares) at Dec. 31, 2018		55,847
Increase (Decrease) in Stockholders' Equity
Net income	37,220
Other comprehensive income	9,100
Repurchases of common stock	$ (11,300)
Repurchases of common stock (in shares)	(200)
Balance at end of period at Jun. 30, 2019	$ 1,209,467	$ 559	648,805	(214,271)	774,374
Balance ending of period (in shares) at Jun. 30, 2019		55,859
Balance at beginning of period at Mar. 31, 2019	1,171,965	$ 558	652,624	(219,347)	738,130
Balance beginning of period (in shares) at Mar. 31, 2019		55,828
Increase (Decrease) in Stockholders' Equity
Net income	36,244				36,244
Other comprehensive income	5,076			5,076
Stock-based compensation	3,834		3,834
Issuance of restricted shares, net of shares remitted and tax withholdings	(2,704)	$ 1	(2,705)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		105
Repurchases of common stock	$ (4,948)		(4,948)
Repurchases of common stock (in shares)	(100)	(74)
Balance at end of period at Jun. 30, 2019	$ 1,209,467	$ 559	$ 648,805	$ (214,271)	$ 774,374
Balance ending of period (in shares) at Jun. 30, 2019		55,859