Fair Value Measurements (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Assets:
Reverse Repurchase Agreements	$ 2,968,000,000	$ 0
Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	358,600,000	439,400,000
Derivative contracts	7,000,000	1,800,000
Plan assets for deferred compensation	15,100,000	14,300,000
Total	3,378,300,000	3,656,500,000
Liabilities:
Derivative contracts	3,200,000	14,400,000
Contingent consideration obligations	293,700,000	293,900,000	269,900,000	151,000,000
Total	296,900,000	308,300,000
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	1,001,000,000
Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	1,657,800,000
Fair Value, Measurements, Recurring [Member] | Mortgage and other asset backed securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	512,900,000
Fair Value, Measurements, Recurring [Member] | Marketable equity securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	11,600,000	9,000,000
Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	18,000,000	20,300,000	22,100,000	23,500,000
Quoted Prices in Active Markets, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	0	0
Reverse Repurchase Agreements	0
Derivative contracts	0	0
Plan assets for deferred compensation	0	0
Total	11,600,000	9,000,000
Liabilities:
Derivative contracts	0	0
Contingent consideration obligations	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] | Marketable equity securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	11,600,000	9,000,000
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) [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	358,600,000	439,400,000
Reverse Repurchase Agreements	2,968,000,000
Derivative contracts	7,000,000	1,800,000
Plan assets for deferred compensation	15,100,000	14,300,000
Total	3,348,700,000	3,627,200,000
Liabilities:
Derivative contracts	3,200,000	14,400,000
Contingent consideration obligations	0	0
Total	3,200,000	14,400,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	1,001,000,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	1,657,800,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and other asset backed securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	512,900,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Marketable equity securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	0	0
Reverse Repurchase Agreements	0
Derivative contracts	0	0
Plan assets for deferred compensation	0	0
Total	18,000,000	20,300,000
Liabilities:
Derivative contracts	0	0
Contingent consideration obligations	293,700,000	293,900,000
Total	293,700,000	293,900,000
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Government securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | 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) [Member] | Fair Value, Measurements, Recurring [Member] | Marketable equity securities [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Venture capital investments [Member]
Assets:
Fair Value, Measured on Recurring Basis, Investments	$ 18,000,000	$ 20,300,000