CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balances at Dec. 31, 2011	$ 1,462,940	$ 641	$ 216,966	$ (1,544)	$ 1,251,157	$ (4,280)
Balances (in shares) at Dec. 31, 2011		(64,145,482)		(81,067)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(54,249)				(54,249)
Other comprehensive income (loss)	(4,734)					(4,734)
Cash dividends, $ 0.10 per share	(6,511)				(6,511)
Issuance of common stock under Employee Stock Purchase Plan	2,776	1	2,775
Issuance of common stock under Employee Stock Purchase Plan (in shares)		66,485
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings	(21,622)	9	(21,631)
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		929,375
Issuance of common stock upon stock option exercises	3,040	2	29,862	323
Stock Issued During Period, Value, Stock Options Exercised			3,038
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures				30,486
Issuance of common stock upon stock option exercises (in shares)		240,368
Conversion of 3.50% Senior Convertible Notes to common stock, including income tax benefit of conversion	2,641	9	2,632
Conversion of 3.50% Senior Convertible Notes to common stock, including income tax benefit of conversion (shares)		864,106
Stock-based compensation expense	30,185
Balances at Dec. 31, 2012	1,414,466	662	233,642	(1,221)	1,190,397	(9,014)
Balances (in shares) at Dec. 31, 2012		(66,245,816)		(50,581)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Increase (Decrease) in Stockholders' Equity
Net income (loss)	170,935				170,935
Other comprehensive income (loss)	3,598					3,598
Cash dividends, $ 0.10 per share	(6,663)				(6,663)
Issuance of common stock under Employee Stock Purchase Plan	3,672	1	3,671
Issuance of common stock under Employee Stock Purchase Plan (in shares)		77,427
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 vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		526,852
Issuance of common stock upon stock option exercises	3,186	3	31,949	398
Stock Issued During Period, Value, Stock Options Exercised			3,183
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures				28,169
Issuance of common stock upon stock option exercises (in shares)		228,758
Stock-based compensation expense	32,347
Other income tax benefit (expense)	(1,500)		(1,500)
Balances at Dec. 31, 2013	1,606,821	671	257,720	(823)	1,354,669	(5,416)
Balances (in shares) at Dec. 31, 2013		(67,078,853)		(22,412)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Increase (Decrease) in Stockholders' Equity
Net income (loss)	666,051				666,051
Other comprehensive income (loss)	(5,896)					(5,896)
Cash dividends, $ 0.10 per share	(6,723)				(6,723)
Issuance of common stock under Employee Stock Purchase Plan	4,061	1	4,060
Issuance of common stock under Employee Stock Purchase Plan (in shares)		83,136
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 vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		256,718
Issuance of common stock upon stock option exercises	816	0	31,871	823
Stock Issued During Period, Value, Stock Options Exercised		0	816
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		5,265		22,412
Issuance of common stock upon stock option exercises (in shares)		39,088
Stock-based compensation expense	32,694
Other income tax benefit (expense)	545		545
Balances at Dec. 31, 2014	$ 2,286,655	$ 675	$ 283,295	$ 0	$ 2,013,997	$ (11,312)
Balances (in shares) at Dec. 31, 2014		(67,463,060)		0