Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Liabilities:
Contingent consideration	$ 151.0	$ 81.2	$ 0
Fair Value, Measurements, Recurring [Member]
Assets:
Cash Equivalents, Fair Value Disclosure	399.8	651.8
Derivative contracts	39.5	1.3
Plan assets for deferred compensation	11.6	13.0
Total	3,067.4	1,922.9
Liabilities:
Derivative contracts	0.5	12.2
Contingent consideration	151.0	81.2
Total	151.5	93.4
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	602.6	313.0
Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	1,716.5	785.3
Fair Value, Measurements, Recurring [Member] | Mortgage and other asset backed securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	273.8	92.9
Fair Value, Measurements, Recurring [Member] | Strategic investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0.1	44.8
Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	23.5	20.8
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash Equivalents, Fair Value Disclosure	0	0
Derivative contracts	0	0
Plan assets for deferred compensation	0	0
Total	0.1	44.8
Liabilities:
Derivative contracts	0	0
Contingent consideration	0	0
Total	0	0
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and other asset backed securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Strategic investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0.1	44.8
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member]
Assets:
Cash Equivalents, Fair Value Disclosure	399.8	651.8
Derivative contracts	39.5	1.3
Plan assets for deferred compensation	11.6	13.0
Total	3,043.8	1,857.3
Liabilities:
Derivative contracts	0.5	12.2
Contingent consideration	0	0
Total	0.5	12.2
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	602.6	313.0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	1,716.5	785.3
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member] | Mortgage and other asset backed securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	273.8	92.9
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member] | Strategic investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member]
Assets:
Cash Equivalents, Fair Value Disclosure	0	0
Derivative contracts	0	0
Plan assets for deferred compensation	0	0
Total	23.5	20.8
Liabilities:
Derivative contracts	0	0
Contingent consideration	151.0	81.2
Total	151.0	81.2
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member] | Mortgage and other asset backed securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member] | Strategic investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	$ 23.5	$ 20.8