Fair Value (Details) (USD $) In Millions	Jun. 30, 2011
Assets measured at fair value on a recurring basis
Cash and cash equivalents	$ 632.8
Short-term investments	29.0
Foreign currency hedges	0.5
Total Assets	662.3
Liabilities measured at fair value on a recurring basis
Foreign currency hedges	5.8
Total Liabilities	5.8
Level 1 [Member]
Assets measured at fair value on a recurring basis
Cash and cash equivalents	632.8
Short-term investments	29.0
Foreign currency hedges	0
Total Assets	661.8
Level 1 [Member]
Liabilities measured at fair value on a recurring basis
Foreign currency hedges	0
Total Liabilities	0
Level 2 [Member]
Assets measured at fair value on a recurring basis
Cash and cash equivalents	0
Short-term investments	0
Foreign currency hedges	0.5
Total Assets	0.5
Level 2 [Member]
Liabilities measured at fair value on a recurring basis
Foreign currency hedges	5.8
Total Liabilities	5.8
Level 3 [Member]
Assets measured at fair value on a recurring basis
Cash and cash equivalents	0
Short-term investments	0
Foreign currency hedges	0
Total Assets	0
Level 3 [Member]
Liabilities measured at fair value on a recurring basis
Foreign currency hedges	0
Total Liabilities	$ 0