Fair Value Measurement (Assets and Liabilities That are Measured and Not Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financial liabilities:
Convertible bonds	$ 1,100.0	$ 0
Convertible Debt, Current		1,100.0
Estimated fair value
Financial liabilities:
Building financing obligation Fair value	8.5	9.7
Recurring Basis | Carrying value
Financial assets:
Available-for-sale securities	11.2	7.4
Contingent consideration receivable	40.2	37.8
Foreign exchange contracts, asset	2.6	3.4
Financial liabilities:
Foreign exchange contracts, liability	1.9	0.4
Recurring Basis | Level 1
Financial assets:
Available-for-sale securities	11.2	7.4
Contingent consideration receivable	0	0
Foreign exchange contracts, asset	0	0
Financial liabilities:
Foreign exchange contracts, liability	0	0
Recurring Basis | Level 2
Financial assets:
Available-for-sale securities	0	0
Contingent consideration receivable	0	0
Foreign exchange contracts, asset	2.6	3.4
Financial liabilities:
Foreign exchange contracts, liability	1.9	0.4
Recurring Basis | Level 3
Financial assets:
Available-for-sale securities	0	0
Contingent consideration receivable	40.2	37.8
Foreign exchange contracts, asset	0	0
Financial liabilities:
Foreign exchange contracts, liability	0	0
Recurring Basis | Estimated fair value
Financial assets:
Available-for-sale securities	11.2	7.4
Contingent consideration receivable	40.2	37.8
Foreign exchange contracts, asset	2.6	3.4
Financial liabilities:
Foreign exchange contracts, liability	1.9	0.4
Nonrecurring Basis | Carrying value
Financial liabilities:
Convertible bonds	1,100.0
Convertible Debt, Current		1,100.0
Building financing obligation Carrying value	8.4	8.2
Nonrecurring Basis | Estimated fair value
Financial liabilities:
Convertible bonds	1,314.2
Convertible Debt, Current		$ 1,309.7