CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Balances, Common Shares, Beginning at Dec. 31, 2012		66,245,816
Balances, Beginning at Dec. 31, 2012	$ 1,414,466	$ 662	$ 233,642		$ 1,190,397	$ (9,014)
Balances, Treasury Shares, Beginning at Dec. 31, 2012				(50,581)
Balances, Treasury Stock, Value, Beginning at Dec. 31, 2012				$ (1,221)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	170,935				170,935
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	3,598					3,598
Cash dividends, $ 0.10 per share	(6,663)				(6,663)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		77,427
Issuance of common stock under Employee Stock Purchase Plan	3,672	$ 1	3,671
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		526,852
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings	$ (16,220)	$ 5	(16,225)
Issuance of common stock upon stock option exercises (in shares)	228,758	228,758
Issuance of common stock upon stock option exercises	$ 3,186	$ 3	3,183
Stock-based compensation expense (in shares)		0		28,169
Stock-based compensation expense	32,347	$ 0	31,949	$ 398
Other income tax benefit (expense)	1,500		1,500
Balances, Common Shares, Ending at Dec. 31, 2013		67,078,853
Balances, Ending at Dec. 31, 2013	$ 1,606,821	$ 671	257,720		1,354,669	(5,416)
Balances, Treasury Shares, Ending at Dec. 31, 2013				(22,412)
Balances, Treasury Stock, Value, Ending at Dec. 31, 2013				$ (823)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Increase (Decrease) in Stockholders' Equity
Net income (loss)	$ 666,051				666,051
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(5,896)					(5,896)
Cash dividends, $ 0.10 per share	(6,723)				(6,723)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		83,136
Issuance of common stock under Employee Stock Purchase Plan	4,061	$ 1	4,060
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		256,718
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings	$ (10,624)	$ 3	(10,627)
Issuance of common stock upon stock option exercises (in shares)	39,088	39,088
Issuance of common stock upon stock option exercises	$ 816	$ 0	816
Stock-based compensation expense (in shares)		5,265		22,412
Stock-based compensation expense	32,694	$ 0	31,871	$ 823
Other income tax benefit (expense)	(545)		(545)
Balances, Common Shares, Ending at Dec. 31, 2014		67,463,060
Balances, Ending at Dec. 31, 2014	$ 2,286,655	$ 675	283,295		2,013,997	(11,312)
Balances, Treasury Shares, Ending at Dec. 31, 2014				0
Balances, Treasury Stock, Value, Ending at Dec. 31, 2014				$ 0
Common Stock, Dividends, Per Share, Declared	$ 0.10
Increase (Decrease) in Stockholders' Equity
Net income (loss)	$ (447,710)				(447,710)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(2,090)					(2,090)
Cash dividends, $ 0.10 per share	(6,772)				(6,772)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		197,214
Issuance of common stock under Employee Stock Purchase Plan	4,844	$ 2	4,842
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		375,523
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings	(8,678)	$ 4	(8,682)
Stock-based compensation expense (in shares)		39,903		0
Stock-based compensation expense	27,467	$ 0	27,467	$ 0
Other income tax benefit (expense)	(1,315)		(1,315)
Balances, Common Shares, Ending at Dec. 31, 2015		68,075,700
Balances, Ending at Dec. 31, 2015	$ 1,852,401	$ 681	$ 305,607		$ 1,559,515	$ (13,402)
Balances, Treasury Shares, Ending at Dec. 31, 2015				0
Balances, Treasury Stock, Value, Ending at Dec. 31, 2015				$ 0