CONDENSED 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)	Convertible Debt [Member]
Balances at Dec. 31, 2009	$ 973,570	$ 629	$ 160,516	$ (1,204)	$ 851,583	$ (37,954)
Balances (in shares) at Dec. 31, 2009		62,899,122		(126,893)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Comprehensive income, net of tax:
Net income (loss)	196,837
Other comprehensive income (loss)	22,472					22,472
Cash dividends, $ 0.10 per share	(6,297)				(6,297)
Issuance of common stock under Employee Stock Purchase Plan	1,670	1	1,669
Issuance of common stock under Employee Stock Purchase Plan (in shares)		52,948
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings	(2,093)	1	(2,094)
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		113,103
Issuance of common stock upon stock option exercises (in shares)		346,377
Issuance of common stock upon stock option exercises, including income tax benefit	5,624	3	5,621
Stock-based compensation expense, Value	26,743		25,962	781
Stock-based compensation expense, Shares		1,250		24,258
Balances at Dec. 31, 2010	1,218,526	634	191,674	(423)	1,042,123	(15,482)
Balances (in shares) at Dec. 31, 2010		63,412,800		(102,635)
Common Stock, Dividends, Per Share, Declared	$ 0.10
Comprehensive income, net of tax:
Net income (loss)	215,416
Other comprehensive income (loss)	11,202					11,202
Cash dividends, $ 0.10 per share	(6,382)				(6,382)
Issuance of common stock under Employee Stock Purchase Plan	2,300	0	2,300
Issuance of common stock under Employee Stock Purchase Plan (in shares)		41,358
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings	(9,973)	3	(9,976)
Issuance of common stock upon vesting of RSUs and settlement of PSUs, net of shares used for tax withholdings (in shares)		278,773
Issuance of common stock upon stock option exercises (in shares)		412,551
Issuance of common stock upon stock option exercises, including income tax benefit	5,027	4	5,023
Stock-based compensation expense, Value	26,824		27,945	(1,121)
Stock-based compensation expense, Shares		0		21,568
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
Comprehensive income, net of tax:
Net income (loss)	(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 (in shares)		240,368
Issuance of common stock upon stock option exercises, including income tax benefit	3,040	2	3,038
Conversion of 3.50% Senior Convertible Notes to common stock, including income tax benefit of conversion (in shares)		864,106					864,106
Conversion of 3.50% Senior Convertible Notes to common stock, including income tax benefit of conversion	2,641	9	2,632				281,300
Stock-based compensation expense, Value	30,185		29,862	323
Stock-based compensation expense, Shares		0		30,486
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)