UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - 9 months ended Sep. 30, 2018 - 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	49,205				49,205
Other comprehensive loss	(13,098)			(13,098)
Stock-based compensation	10,726		10,726
Issuance of restricted shares, net of shares remitted and tax withholdings	(2,566)	$ 1	(2,567)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		133
Repurchases of common stock	$ (33,581)	$ (6)	(33,575)
Repurchases of common stock (in shares)	(600)	(636)
Balance at end of period at Sep. 30, 2018	$ 1,197,324	$ 560	$ 661,546	$ (185,505)	720,723
Balance ending of period (in shares) at Sep. 30, 2018		55,998
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle	$ (1,564)
Cumulative effect of change in accounting principle | Accounting Standards Update 2016-16					$ (1,564)