Financial Instruments (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments	$ 3,232.4	$ 2,966.8
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,554.5	2,097.9
Short-term investments, debt securities	49.0	24.2
Equity investments without readily determinable fair values	384.3	373.9
Noncurrent investments	3,232.4	2,966.8
Long-term debt, including current portion	(16,204.5)	(16,595.3)
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	20.9	9.9
Noncurrent investments, debt securities	109.1	78.7
Carrying Amount | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	7.6	2.8
Noncurrent investments, debt securities	177.8	137.0
Carrying Amount | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	2.3	1.2
Noncurrent investments, debt securities	23.8	24.3
Carrying Amount | Other securities, current investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	18.2	10.3
Carrying Amount | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	102.3	106.4
Carrying Amount | Other securities, noncurrent investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	110.3	110.5
Carrying Amount | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,645.5	1,664.2
Carrying Amount | Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments	679.3	471.8
Cost
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,554.5	2,097.9
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	20.8	9.9
Noncurrent investments, debt securities	108.8	74.3
Cost | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	7.5	2.8
Noncurrent investments, debt securities	175.5	126.8
Cost | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	2.2	1.2
Noncurrent investments, debt securities	23.5	23.7
Cost | Other securities, current investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, debt securities	18.2	10.3
Cost | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncurrent investments, debt securities	99.7	101.4
Cost | Other securities, noncurrent investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	30.1	31.8
Cost | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	386.1	311.6
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,554.5	2,097.9
Long-term debt, including current portion	(17,462.6)	(19,038.9)
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	1,554.5	2,097.9
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
Long-term debt, including current portion	(17,462.6)	(19,038.9)
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
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	20.9	9.9
Noncurrent investments, debt securities	109.1	78.7
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	20.9	9.9
Noncurrent investments, debt securities	109.1	78.7
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	7.6	2.8
Noncurrent investments, debt securities	177.8	137.0
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	7.6	2.8
Noncurrent investments, debt securities	177.8	137.0
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	2.3	1.2
Noncurrent investments, debt securities	23.8	24.3
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	2.3	1.2
Noncurrent investments, debt securities	23.8	24.3
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	18.2	10.3
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	18.2	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	0.0	10.3
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	102.3	106.4
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	102.3	106.4
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	110.3	110.5
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	110.3	110.5
Estimate of Fair Value Measurement | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,645.5	1,664.2
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	1,645.5	1,664.2
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