CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Shares Held Under Employee Participation Plan	Additional Paid-in Capital	Accumulated Other Comprehensive loss	Accumulated Earnings
Beginning balance at Dec. 31, 2014	$ 1,262,871	$ 589	$ (469)	$ 805,029	$ (110,842)	$ 568,564
Beginning balance (in shares) at Dec. 31, 2014		58,903
Increase (Decrease) in Stockholders' Equity
Net (loss) income	44,102					44,102
Other comprehensive loss	(144,050)				(144,050)
Stock-based compensation	8,550			8,550
Issuance of restricted shares, net of shares remitted	(2,159)	$ 1		(2,160)
Issuance of restricted shares, net of shares remitted (in shares)		100
Exercise of stock options	397			397
Exercise of stock options (in shares)		12
Repurchases of common stock	(73,347)	$ (14)		(73,333)
Repurchases of common stock (in shares)		(1,422)
Net tax benefit on stock-based awards	(82)			(82)
Ending balance at Dec. 31, 2015	1,096,282	$ 576	(469)	738,401	(254,892)	612,666
Ending balance (in shares) at Dec. 31, 2015		57,593
Increase (Decrease) in Stockholders' Equity
Net (loss) income	(39,873)					(39,873)
Other comprehensive loss	40,566				40,566
Stock-based compensation	10,481			10,481
Issuance of restricted shares, net of shares remitted	(2,819)	$ 1		(2,820)
Issuance of restricted shares, net of shares remitted (in shares)		136
Exercise of stock options	627			627
Exercise of stock options (in shares)		22
Repurchases of common stock	(22,188)	$ (4)		(22,184)
Repurchases of common stock (in shares)		(453)
Net tax benefit on stock-based awards	1,165			1,165
Ending balance at Dec. 31, 2016	1,084,241	$ 573	(469)	725,670	(214,326)	572,793
Ending balance (in shares) at Dec. 31, 2016		57,298
Increase (Decrease) in Stockholders' Equity
Net (loss) income	100,739					100,739
Other comprehensive loss	41,919				41,919
Stock-based compensation	13,146			13,146
Issuance of restricted shares, net of shares remitted	(3,149)	$ 1		(3,150)
Issuance of restricted shares, net of shares remitted (in shares)		133
Exercise of stock options	46			46
Shares held under employee participation plan	0		469	(469)
Shares held under employee participation plan (in shares)		(25)
Exercise of stock options (in shares)		2
Repurchases of common stock	(48,971)	$ (9)		(48,962)
Repurchases of common stock (in shares)		(907)
Ending balance at Dec. 31, 2017	1,188,202	$ 565	$ 0	686,962	$ (172,407)	673,082
Ending balance (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting for stock-based compensation	$ 231			$ 681		$ (450)