Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Unrealized Gain(Loss) On Short-Term Investments [Member]	Unrecognized Pension Plan Losses And Prior Service Costs [Member]	Interest Rate Swap Contracts [Member]	Foreign Currency Translation [Member]	Accumulated Earnings [Member]	Total
BALANCE at Dec. 31, 2008	$ 629	$ 400,626	$ (671,841)	$ 241	$ (919)			$ 435,951	$ 164,687
BALANCE, shares at Dec. 31, 2008	34,720,000
Comprehensive income:
Net income								43,333	43,333
Unrealized loss on short-term investments, net of tax				(231)
Total comprehensive income									43,102
Repurchase of common stock pursuant to Board-approved stock repurchase program			(3,782)						(3,782)
Repurchase of common stock pursuant to Board-approved stock repurchase program, shares	(250,000)
Issuance of common stock pursuant to employee stock purchase plan		1,145							1,145
Issuance of common stock pursuant to employee stock purchase plan, shares	88,000
Exercise of stock options		332							332
Exercise of stock options, shares	47,000
Tax benefit of employee stock-based compensation plans		(2,329)							(2,329)
Issuance of restricted common stock pursuant to employee stock-based compensation plans	8	(8)
Issuance of restricted common stock pursuant to employee stock-based compensation plans, shares	847,000
Cancellation of restricted common stock issued pursuant to employee stock-based compensation plans, shares	(131,000)
Repurchase and cancellation of common stock issued pursuant to employee stock-based compensation plans	(1)	(2,779)							(2,780)
Repurchase and cancellation of common stock issued pursuant to employee stock-based compensation plans, shares	(195,000)
Repurchase of Convertible Debt Securities		(897)							(897)
Stock-based employee compensation expense		12,632							12,632
BALANCE at Dec. 31, 2009	636	408,722	(675,623)	10	(919)			479,284	212,110
BALANCE, shares at Dec. 31, 2009	35,126,000
Comprehensive income:
Net income								22,429	22,429
Unrealized loss on short-term investments, net of tax				(6)
Unrealized pension plan gains and prior service costs, net of tax					(22)
Foreign currency translation adjustments							868
Total comprehensive income									23,313
Repurchase of common stock pursuant to Board-approved stock repurchase program			(29,340)						(29,340)
Repurchase of common stock pursuant to Board-approved stock repurchase program, shares	(1,500,000)
Issuance of common stock pursuant to employee stock purchase plan		1,172							1,172
Issuance of common stock pursuant to employee stock purchase plan, shares	70,000
Exercise of stock options		233							233
Exercise of stock options, shares	19,000
Tax benefit of employee stock-based compensation plans		627							627
Issuance of restricted common stock pursuant to employee stock-based compensation plans	8	(8)
Issuance of restricted common stock pursuant to employee stock-based compensation plans, shares	748,000
Cancellation of restricted common stock issued pursuant to employee stock-based compensation plans	(2)	2
Cancellation of restricted common stock issued pursuant to employee stock-based compensation plans, shares	(109,000)
Repurchase and cancellation of common stock issued pursuant to employee stock-based compensation plans	(1)	(4,689)							(4,690)
Repurchase and cancellation of common stock issued pursuant to employee stock-based compensation plans, shares	(233,000)
Repurchase of Convertible Debt Securities		(1,613)							(1,613)
Issuance of 2010 Convertible Notes, net of tax		22,928							22,928
Stock-based employee compensation expense		12,338							12,338
BALANCE at Dec. 31, 2010	641	439,712	(704,963)	4	(897)		868	501,713	237,078
BALANCE, shares at Dec. 31, 2010	34,121,000								34,120,789
Comprehensive income:
Net income								42,282	42,282
Unrealized loss on short-term investments, net of tax				(3)
Unrealized pension plan gains and prior service costs, net of tax					(897)
Unrealized loss on change in fair value of interest rate swap contracts, net of tax						(618)
Foreign currency translation adjustments							(2,866)
Total comprehensive income									37,898
Repurchase of common stock pursuant to Board-approved stock repurchase program			(9,930)						(9,930)
Repurchase of common stock pursuant to Board-approved stock repurchase program, shares	(750,000)
Issuance of common stock pursuant to employee stock purchase plan		1,442							1,442
Issuance of common stock pursuant to employee stock purchase plan, shares	103,000
Exercise of stock options		44							44
Exercise of stock options, shares	3,000
Tax benefit of employee stock-based compensation plans		465							465
Issuance of restricted common stock pursuant to employee stock-based compensation plans	7	(7)
Issuance of restricted common stock pursuant to employee stock-based compensation plans, shares	746,000
Cancellation of restricted common stock issued pursuant to employee stock-based compensation plans	(1)	1
Cancellation of restricted common stock issued pursuant to employee stock-based compensation plans, shares	(170,000)
Repurchase and cancellation of common stock issued pursuant to employee stock-based compensation plans	(2)	(4,433)							(4,435)
Repurchase and cancellation of common stock issued pursuant to employee stock-based compensation plans, shares	(231,000)
Stock-based employee compensation expense		12,152							12,152
BALANCE at Dec. 31, 2011	$ 645	$ 449,376	$ (714,893)	$ 1	$ (1,794)	$ (618)	$ (1,998)	$ 543,995	$ 274,714
BALANCE, shares at Dec. 31, 2011	33,822,000								33,822,232