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 Income (loss)	Accumulated Earnings
Balance at Dec. 31, 2012	$ 1,432,072	$ 604	$ (469)	$ 880,979	$ 49,632	$ 501,326
Balance (in shares) at Dec. 31, 2012		60,385
Increase (Decrease) in Stockholders' Equity
Net income (loss)	95,566					95,566
Other comprehensive income	(69,188)				(69,188)
Stock-based compensation	8,946			8,946
Stock-based compensation (in shares)		74
Issuance of restricted shares, net of shares remitted	(731)			(731)
Issuance of restricted shares, net of shares remitted (in shares)		(19)
Issuance of common stock, net of issuance cost	(250)			(250)
Exercise of stock options	400	$ 3		397
Exercise of stock options (in shares)		61
Net tax benefit on stock-based awards	1,399			1,399
Employee stock purchase plan	7,425			7,425
Employee stock purchase plan (in shares)		171
Balance at Dec. 31, 2013	1,475,639	$ 607	(469)	898,165	(19,556)	596,892
Balance (in shares) at Dec. 31, 2013		60,672
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(28,328)					(28,328)
Other comprehensive income	(91,286)				(91,286)
Stock-based compensation	8,800			8,800
Stock-based compensation (in shares)		0
Issuance of restricted shares, net of shares remitted	(2,793)	$ 1		(2,794)
Issuance of restricted shares, net of shares remitted (in shares)		113
Repurchases of common stock	(104,341)	$ (20)		(104,321)
Repurchased of common stock (in shares)		(1,973)
Net tax benefit on stock-based awards	816			816
Employee stock purchase plan	4,364	$ 1		4,363
Employee stock purchase plan (in shares)		91
Balance at Dec. 31, 2014	1,262,871	$ 589	(469)	805,029	(110,842)	568,564
Balance (in shares) at Dec. 31, 2014		58,903
Increase (Decrease) in Stockholders' Equity
Net income (loss)	44,102					44,102
Other comprehensive income	(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)
Repurchased of common stock (in shares)		(1,422)
Net tax benefit on stock-based awards	(82)			(82)
Balance at Dec. 31, 2015	$ 1,096,282	$ 576	$ (469)	$ 738,401	$ (254,892)	$ 612,666
Balance (in shares) at Dec. 31, 2015		57,593