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	Dec. 31, 2011		Dec. 31, 2010
Financial liabilities:
Convertible bonds	$ 0		$ 1,100.0
Convertible Debt, Current	1,100.0		0
Carrying value
Financial liabilities:
Convertible bonds			1,100.0
Building financing obligation	8.2		8.4
Estimated fair value
Financial liabilities:
Convertible bonds			1,139.8
Building financing obligation	9.7		8.2
Recurring Basis
Financial assets:
Available-for-sale securities	7.4	[1]	83.9	[1]
Contingent consideration receivable	37.8	[2]	61.0	[2]
Foreign exchange contracts, asset	3.4		3.7
Financial liabilities:
Foreign exchange contracts, liability	0.4		2.7
Recurring Basis | Carrying value
Financial assets:
Available-for-sale securities	7.4	[1]	83.9	[1]
Contingent consideration receivable	37.8	[2]	61.0	[2]
Foreign exchange contracts, asset	3.4		3.7
Financial liabilities:
Foreign exchange contracts, liability	0.4		2.7
Recurring Basis | Level 1
Financial assets:
Available-for-sale securities	7.4	[1]	83.9	[1]
Contingent consideration receivable	0	[2]	0	[2]
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	[1]	0	[1]
Contingent consideration receivable	0	[2]	0	[2]
Foreign exchange contracts, asset	3.4		3.7
Financial liabilities:
Foreign exchange contracts, liability	0.4		2.7
Recurring Basis | Level 3
Financial assets:
Available-for-sale securities	0	[1]	0	[1]
Contingent consideration receivable	37.8	[2]	61.0	[2]
Foreign exchange contracts, asset	0		0
Financial liabilities:
Foreign exchange contracts, liability	0		0
Nonrecurring Basis | Carrying value
Financial liabilities:
Convertible Debt, Current	1,100.0
Nonrecurring Basis | Estimated fair value
Financial liabilities:
Convertible Debt, Current	$ 1,309.7

[1] Available-for-sale securities are included within Investments in the consolidated balance sheet.

[2] Contingent consideration receivable is included within Prepaid expenses and other current assets and Other non-current assets in the consolidated balance sheet.