Short-Term And Long-Term Investments (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2011

Dec. 31, 2010

Short-Term And Long-Term Investments [Abstract]

Schedule Of Short-Term And Long-Term Investments By Contractual Maturity

	Contractual Maturity Date For the Years Ending December 31,										Unrealized Gain (Loss)			Aggregate Fair Value at September 30, 2011
	2011		2012		2013		2014		Total Book Value at September 30, 2011
Certificates of deposit	$	3,919	$	38,962	$	17,240	$	0	$	60,121	$	15		$	60,136
Commercial paper		14,994		24,706		0		0		39,700		(15	)		39,685
Corporate securities		10,558		95,701		41,098		3,100		150,457		64			150,521
U.S. Government agency securities		0		12,497		35,916		0		48,413		5			48,418
Total	$	29,471	$	171,866	$	94,254	$	3,100	$	298,691	$	69		$	298,760

	Contractual Maturity Date For the Years Ending December  31,								Unrealized Gain		Aggregate Fair Value at December 31, 2010
	2011		2012		2013		Total Book Value at December 31, 2010
Certificates of deposit	$	29,844	$	22,748	$	3,093	$	55,685	$	8	$	55,693
Commercial paper		27,439		0		0		27,439		18		27,457
Corporate securities		80,062		63,046		8,809		151,917		598		152,515
U.S. Government agency securities		48,480		28,021		2,000		78,501		38		78,539
Total	$	185,825	$	113,815	$	13,902	$	313,542	$	662	$	314,204

Schedule Of Unrealized Losses And Related Fair Value, Investments With Unrealized Losses

		0000000000		0000000000			0000000000		0000000000			0000000000		0000000000
	Less Than 12 Months To Maturity					12 Months or More To Maturity					Totals at September 30, 2011
	Aggregate Fair Value		Unrealized Losses			Aggregate Fair Value		Unrealized Losses			Aggregate Fair Value		Unrealized Losses
Certificates of deposit	$	8,589	$	(1	)	$	9,982	$	(4	)	$	18,571	$	(5	)
Commercial paper		19,196		(22	)		0		0			19,196		(22	)
Corporate securities		26,680		(94	)		39,142		(186	)		65,822		(280	)
U.S. Government agency securities		0		0			22,320		(7	)		22,320		(7	)
Total	$	54,465	$	(117	)	$	71,444	$	(197	)	$	125,909	$	(314	)

	Less Than 12 Months To Maturity					12 Months or More To Maturity					Totals at December 31, 2010
	Aggregate Fair Value		Unrealized Losses			Aggregate Fair Value		Unrealized Losses			Aggregate Fair Value		Unrealized Losses
Certificates of deposit	$	13,283	$	(21	)	$	1,678	$	(1	)	$	14,961	$	(22	)
Commercial paper		7,486		(1	)		0		0			7,486		(1	)
Corporate securities		19,606		(7	)		18,437		(68	)		38,043		(75	)
U.S. Government agency securities		0		0			16,463		(33	)		16,463		(33	)
Total	$	40,375	$	(29	)	$	36,578	$	(102	)	$	76,953	$	(131