Fair Value Measurements (Summary Of Fair Value Of Financial Assets And Liabilities Measured At Recurring Basis And Valuation Techniques) (Details) (USD $) In Thousands	Sep. 30, 2011		Dec. 31, 2010
Total investments, fair value	$ 62,931		$ 135,750
Total assets	191,306		406,081
Total liabilities	12,027		9,895
Income Approach Valuation Techniques [Member]
Contingent consideration	11,655	[1]	8,515
Income Approach Valuation Techniques [Member] | Level 1 [Member]
Contingent consideration		[1]
Income Approach Valuation Techniques [Member] | Level 2 [Member]
Contingent consideration		[1]
Income Approach Valuation Techniques [Member] | Level 3 [Member]
Contingent consideration	11,655	[1]	8,515
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Money Market Funds [Member]
Total investments, fair value	124,452		268,118
Market Approach Valuation Techniques [Member] | Level 1 [Member] | U.S. Treasury Securities [Member]
Total investments, fair value			24,511
Market Approach Valuation Techniques [Member] | Level 1 [Member] | U.S. Agency Securities [Member]
Total investments, fair value	6,060		35,387
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Corporate Notes/Bonds[Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Certificates/Term Deposits [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Commercial Paper [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Derivative Assets [Member]
Derivative assets		[1]		[1]
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Derivative Liabilities [Member]
Derivative liabilities		[1]		[1]
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Money Market Funds [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 2 [Member] | U.S. Treasury Securities [Member]
Total investments, fair value	3,429
Market Approach Valuation Techniques [Member] | Level 2 [Member] | U.S. Agency Securities [Member]
Total investments, fair value	2,014
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Corporate Notes/Bonds[Member]
Total investments, fair value	49,270		51,181
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Certificates/Term Deposits [Member]
Total investments, fair value	3,286		10,777
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Commercial Paper [Member]
Total investments, fair value			14,984
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Derivative Assets [Member]
Derivative assets	2,795	[1]	1,123	[1]
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Derivative Liabilities [Member]
Derivative liabilities	372	[1]	1,380	[1]
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Money Market Funds [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 3 [Member] | U.S. Treasury Securities [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 3 [Member] | U.S. Agency Securities [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Corporate Notes/Bonds[Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Certificates/Term Deposits [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Commercial Paper [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Derivative Assets [Member]
Derivative assets		[1]		[1]
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Derivative Liabilities [Member]
Derivative liabilities		[1]		[1]
Market Approach Valuation Techniques [Member] | Money Market Funds [Member]
Total investments, fair value	124,452		268,118
Market Approach Valuation Techniques [Member] | U.S. Treasury Securities [Member]
Total investments, fair value	3,429		24,511
Market Approach Valuation Techniques [Member] | U.S. Agency Securities [Member]
Total investments, fair value	8,074		35,387
Market Approach Valuation Techniques [Member] | Corporate Notes/Bonds[Member]
Total investments, fair value	49,270		51,181
Market Approach Valuation Techniques [Member] | Certificates/Term Deposits [Member]
Total investments, fair value	3,286		10,777
Market Approach Valuation Techniques [Member] | Commercial Paper [Member]
Total investments, fair value			14,984
Market Approach Valuation Techniques [Member] | Derivative Assets [Member]
Derivative assets	2,795	[1]	1,123	[1]
Market Approach Valuation Techniques [Member] | Derivative Liabilities [Member]
Derivative liabilities	372	[1]	1,380	[1]
Level 1 [Member]
Total assets	130,512		328,016
Total liabilities
Level 2 [Member]
Total assets	60,794		78,065
Total liabilities	372		1,380
Level 3 [Member]
Total assets
Total liabilities	$ 11,655		$ 8,515

[1] See Note 15 - Derivative Instruments for details.