Fair Value Measurements (Schedule of Financial Measured at Fair Value) (Details) (USD $) In Thousands	Jun. 30, 2011
Assets at fair value	$ 423,070
Money Market Funds [Member]
Assets at fair value	50,131	[1]
Money Market Funds [Member] | Level 1 [Member]
Assets at fair value	50,131	[1]
Money Market Funds [Member] | Level 2 [Member]
Assets at fair value		[1]
Money Market Funds [Member] | Level 3 [Member]
Assets at fair value		[1]
Commercial Paper [Member]
Assets at fair value	266,184	[2]
Commercial Paper [Member] | Level 1 [Member]
Assets at fair value		[2]
Commercial Paper [Member] | Level 2 [Member]
Assets at fair value	266,184	[2]
Commercial Paper [Member] | Level 3 [Member]
Assets at fair value		[2]
Other Fixed Income Securities [Member]
Assets at fair value	106,755	[2]
Other Fixed Income Securities [Member] | Level 1 [Member]
Assets at fair value		[2]
Other Fixed Income Securities [Member] | Level 2 [Member]
Assets at fair value	106,755	[2]
Other Fixed Income Securities [Member] | Level 3 [Member]
Assets at fair value		[2]
Acquisition-related Contingent Consideration [Member]
Liabilities at fair value	24,110
Acquisition-related Contingent Consideration [Member] | Level 1 [Member]
Liabilities at fair value
Acquisition-related Contingent Consideration [Member] | Level 2 [Member]
Liabilities at fair value
Acquisition-related Contingent Consideration [Member] | Level 3 [Member]
Liabilities at fair value	24,110
Level 1 [Member]
Assets at fair value	50,131
Level 2 [Member]
Assets at fair value	372,939
Level 3 [Member]
Assets at fair value

[1] Included in cash and cash equivalents on our balance sheets.

[2] Included in either cash and cash equivalents or short-term investments on our balance sheets.