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, 2015	$ 1,096,282	$ 576	$ (469)	$ 738,401	$ (254,892)	$ 612,666
Beginning balance (in shares) at Dec. 31, 2015		57,593
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(39,873)					(39,873)
Other comprehensive income	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 income (loss)	100,739					100,739
Other comprehensive income	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
Exercise of stock options (in shares)		2
Shares held under employee participation plan	0		469	(469)
Shares held under employee participation plan (in shares)		(25)
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 principle	231			681		(450)
Net income (loss)	65,636					65,636
Other comprehensive income	(50,964)				(50,964)
Stock-based compensation	16,792			16,792
Issuance of restricted shares, net of shares remitted	(3,266)	$ 1		(3,267)
Issuance of restricted shares, net of shares remitted (in shares)		160
Repurchases of common stock	(45,080)	$ (8)		(45,072)
Repurchases of common stock (in shares)		(814)
Ending balance at Dec. 31, 2018	1,169,756	$ 558	$ 0	$ 655,415	$ (223,371)	737,154
Ending balance (in shares) at Dec. 31, 2018		55,847
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle	$ (1,564)					$ (1,564)