Financial Instruments (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments	$ 2,406.4	$ 1,962.4
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,109.7	1,025.4
Short-term investments, debt securities	22.8	101.0
Equity investments without readily determinable fair values	357.5	405.0
Noncurrent investments	2,406.4	1,962.4
Short-term commercial paper borrowings	(1,258.8)	(1,494.2)
Long-term debt, including current portion	(15,069.4)	(13,823.0)
Carrying Amount | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	11.9	7.2
Noncurrent investments, debt securities	79.1	77.2
Carrying Amount | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	4.7	81.4
Noncurrent investments, debt securities	131.7	271.1
Carrying Amount | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	3.6	2.6
Noncurrent investments, debt securities	26.4	30.0
Carrying Amount | Other securities, current investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	2.6	9.8
Carrying Amount | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	100.2	101.1
Carrying Amount | Other securities, noncurrent investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	49.6	60.0
Carrying Amount | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,292.4	718.6
Carrying Amount | Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments	369.5	299.4
Cost
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,109.7	1,025.4
Cost | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	11.8	7.2
Noncurrent investments, debt securities	74.4	76.3
Cost | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	4.6	81.1
Noncurrent investments, debt securities	123.2	267.8
Cost | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	3.6	2.6
Noncurrent investments, debt securities	25.7	29.6
Cost | Other securities, current investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	2.6	9.8
Cost | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	95.2	99.6
Cost | Other securities, noncurrent investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	23.4	27.4
Cost | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	241.2	254.4
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,109.7	1,025.4
Short-term commercial paper borrowings	(1,255.7)	(1,491.6)
Long-term debt, including current portion	(17,011.0)	(15,150.0)
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,109.7	1,025.4
Short-term commercial paper borrowings	0.0	0.0
Long-term debt, including current portion	0.0	0.0
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Short-term commercial paper borrowings	(1,255.7)	(1,491.6)
Long-term debt, including current portion	(17,011.0)	(15,150.0)
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Short-term commercial paper borrowings	0.0	0.0
Long-term debt, including current portion	0.0	0.0
Estimate of Fair Value Measurement | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	11.9	7.2
Noncurrent investments, debt securities	79.1	77.2
Estimate of Fair Value Measurement | U.S. government and agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	11.9	7.2
Noncurrent investments, debt securities	79.1	77.2
Estimate of Fair Value Measurement | U.S. government and agency securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | U.S. government and agency securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	4.7	81.4
Noncurrent investments, debt securities	131.7	271.1
Estimate of Fair Value Measurement | Corporate debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Corporate debt securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	4.7	81.4
Noncurrent investments, debt securities	131.7	271.1
Estimate of Fair Value Measurement | Corporate debt securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	3.6	2.6
Noncurrent investments, debt securities	26.4	30.0
Estimate of Fair Value Measurement | Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Asset-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	3.6	2.6
Noncurrent investments, debt securities	26.4	30.0
Estimate of Fair Value Measurement | Asset-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Other securities, current investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	2.6	9.8
Estimate of Fair Value Measurement | Other securities, current investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Other securities, current investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Other securities, current investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	2.6	9.8
Estimate of Fair Value Measurement | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	100.2	101.1
Estimate of Fair Value Measurement | Mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	100.2	101.1
Estimate of Fair Value Measurement | Mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	0.0	0.0
Estimate of Fair Value Measurement | Other securities, noncurrent investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	49.6	60.0
Estimate of Fair Value Measurement | Other securities, noncurrent investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0.0	0.0
Estimate of Fair Value Measurement | Other securities, noncurrent investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0.0	0.0
Estimate of Fair Value Measurement | Other securities, noncurrent investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	49.6	60.0
Estimate of Fair Value Measurement | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,292.4	718.6
Estimate of Fair Value Measurement | Marketable equity securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,292.4	718.6
Estimate of Fair Value Measurement | Marketable equity securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0.0	0.0
Estimate of Fair Value Measurement | Marketable equity securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 0.0	$ 0.0