Fair Value Measurements (Summary Of Fair Value Of Financial Assets And Liabilities Measured At Recurring Basis And Valuation Techniques) (Details) (USD $) In Thousands	Jun. 30, 2011		Dec. 31, 2010
Total investments, fair value	$ 77,057		$ 135,750
Total assets	184,211		406,081
Contingent consideration	5,700	[1]
Total liabilities	12,173		9,895
Income Approach Valuation Techniques [Member]
Contingent consideration	11,513		8,515
Income Approach Valuation Techniques [Member] | Level 1 [Member]
Contingent consideration
Income Approach Valuation Techniques [Member] | Level 2 [Member]
Contingent consideration
Income Approach Valuation Techniques [Member] | Level 3 [Member]
Contingent consideration	11,513		8,515
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Money Market Funds [Member]
Total investments, fair value	103,320		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	11,096		35,387
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Derivative Assets [Member]
Derivative assets		[2]		[2]
Market Approach Valuation Techniques [Member] | Level 1 [Member] | Derivative Liabilities [Member]
Derivative liabilities		[2]
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	3,435
Market Approach Valuation Techniques [Member] | Level 2 [Member] | U.S. Agency Securities [Member]
Total investments, fair value
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Corporate Notes/Bonds[Member]
Total investments, fair value	54,774		51,181
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Certificates/Term Deposits [Member]
Total investments, fair value	3,892		10,777
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Commercial Paper [Member]
Total investments, fair value	6,499		14,984
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Derivative Assets [Member]
Derivative assets	1,195	[2]	1,123	[2]
Market Approach Valuation Techniques [Member] | Level 2 [Member] | Derivative Liabilities [Member]
Derivative liabilities	660	[2]	1,380	[2]
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		[2]		[2]
Market Approach Valuation Techniques [Member] | Level 3 [Member] | Derivative Liabilities [Member]
Derivative liabilities		[2]
Market Approach Valuation Techniques [Member] | Money Market Funds [Member]
Total investments, fair value	103,320		268,118
Market Approach Valuation Techniques [Member] | U.S. Treasury Securities [Member]
Total investments, fair value	3,435		24,511
Market Approach Valuation Techniques [Member] | U.S. Agency Securities [Member]
Total investments, fair value	11,096		35,387
Market Approach Valuation Techniques [Member] | Corporate Notes/Bonds[Member]
Total investments, fair value	54,774		51,181
Market Approach Valuation Techniques [Member] | Certificates/Term Deposits [Member]
Total investments, fair value	3,892		10,777
Market Approach Valuation Techniques [Member] | Commercial Paper [Member]
Total investments, fair value	6,499		14,984
Market Approach Valuation Techniques [Member] | Derivative Assets [Member]
Derivative assets	1,195	[2]	1,123	[2]
Market Approach Valuation Techniques [Member] | Derivative Liabilities [Member]
Derivative liabilities	660	[2]	1,380	[2]
Level 1 [Member]
Total assets	114,416		328,016
Total liabilities
Level 2 [Member]
Total assets	69,795		78,065
Total liabilities	660		1,380
Level 3 [Member]
Total assets
Total liabilities	$ 11,513		$ 8,515

[1] We enter into earn-out agreements with the shareholders of certain companies we acquire. The earn-out contingent payments are typically based on the acquired company's products' total revenue or sales growth over a specified period after the acquisition date. This also includes contingent consideration relating to our purchase of intellectual property. During the second quarter of 2011, we separately purchased intellectual property and entered into an agreement whereby the former owner has the opportunity to earn an additional amount contingent upon his achievement of certain technology milestones.

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