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 beginning of period (in shares) at Dec. 31, 2018		55,847
Balance beginning of period at Dec. 31, 2018	$ 1,169,756	$ 558	$ 655,415	$ (223,371)	$ 737,154
Increase (Decrease) in Stockholders' Equity
Net income	976				976
Other comprehensive (loss) income	4,024			4,024
Stock-based compensation	5,809		5,809
Issuance of common stock for restricted share vesting, net of employee tax withholdings (in shares)		78
Issuance of common stock for restricted share vesting, net of employee tax withholdings	(2,276)	$ 1	(2,277)
Repurchases of common stock (in shares)		(97)
Repurchases of common stock	(6,324)	$ (1)	(6,323)
Balance ending of period (in shares) at Mar. 31, 2019		55,828
Balance ending of period at Mar. 31, 2019	1,171,965	$ 558	652,624	(219,347)	738,130
Balance beginning of period (in shares) at Dec. 31, 2018		55,847
Balance beginning of period at Dec. 31, 2018	1,169,756	$ 558	655,415	(223,371)	737,154
Increase (Decrease) in Stockholders' Equity
Net income	37,220
Other comprehensive (loss) income	9,100
Balance ending of period (in shares) at Jun. 30, 2019		55,859
Balance ending of period at Jun. 30, 2019	1,209,467	$ 559	648,805	(214,271)	774,374
Balance beginning of period (in shares) at Mar. 31, 2019		55,828
Balance beginning of period at Mar. 31, 2019	1,171,965	$ 558	652,624	(219,347)	738,130
Increase (Decrease) in Stockholders' Equity
Net income	36,244				36,244
Other comprehensive (loss) income	5,076			5,076
Stock-based compensation	3,834		3,834
Issuance of common stock for restricted share vesting, net of employee tax withholdings (in shares)		105
Issuance of common stock for restricted share vesting, net of employee tax withholdings	(2,704)	$ 1	(2,705)
Repurchases of common stock (in shares)		(74)
Repurchases of common stock	(4,948)	$ 0	(4,948)
Balance ending of period (in shares) at Jun. 30, 2019		55,859
Balance ending of period at Jun. 30, 2019	$ 1,209,467	$ 559	648,805	(214,271)	774,374
Increase (Decrease) in Stockholders' Equity
Common stock, par value (in USD per share)	$ 0.01
Common stock, par value (in USD per share)	$ 0.01
Balance beginning of period (in shares) at Dec. 31, 2019		55,798
Balance beginning of period at Dec. 31, 2019	$ 1,269,813	$ 558	644,412	(210,051)	834,894
Increase (Decrease) in Stockholders' Equity
Net income	11,572				11,572
Other comprehensive (loss) income	(59,306)			(59,306)
Stock-based compensation	3,291		3,291
Issuance of common stock for restricted share vesting, net of employee tax withholdings (in shares)		59
Issuance of common stock for restricted share vesting, net of employee tax withholdings	(2,224)	$ 1	(2,225)
Repurchases of common stock (in shares)		(302)
Repurchases of common stock	(17,341)	$ (3)	(17,338)
Balance ending of period (in shares) at Mar. 31, 2020		55,555
Balance ending of period at Mar. 31, 2020	1,205,805	$ 556	628,140	(269,357)	846,466
Balance beginning of period (in shares) at Dec. 31, 2019		55,798
Balance beginning of period at Dec. 31, 2019	1,269,813	$ 558	644,412	(210,051)	834,894
Increase (Decrease) in Stockholders' Equity
Net income	40,595
Other comprehensive (loss) income	(41,778)
Balance ending of period (in shares) at Jun. 30, 2020		55,613
Balance ending of period at Jun. 30, 2020	1,253,971	$ 556	629,755	(251,829)	875,489
Balance beginning of period (in shares) at Mar. 31, 2020		55,555
Balance beginning of period at Mar. 31, 2020	1,205,805	$ 556	628,140	(269,357)	846,466
Increase (Decrease) in Stockholders' Equity
Net income	29,023				29,023
Other comprehensive (loss) income	17,528			17,528
Stock-based compensation	2,786		2,786
Issuance of common stock for restricted share vesting, net of employee tax withholdings (in shares)		58
Issuance of common stock for restricted share vesting, net of employee tax withholdings	(1,171)	$ 0	(1,171)
Balance ending of period (in shares) at Jun. 30, 2020		55,613
Balance ending of period at Jun. 30, 2020	$ 1,253,971	$ 556	$ 629,755	$ (251,829)	$ 875,489
Increase (Decrease) in Stockholders' Equity
Common stock, par value (in USD per share)	$ 0.01