Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	$ 10,051.3	$ 10,018.2
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	6,592.2	6,684.4
U.S. government and government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	2,903.4	2,939.4
Sovereign bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	70.4	64.1
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	279.1	121.1
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	153.7	182.0
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	52.5	27.2
Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,422.7	1,662.8
Assets, Fair Value Disclosure, Total	12,532.7	12,891.0
Measured on a recurring basis | Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	20.7	24.6
Measured on a recurring basis | Restricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,038.0	1,185.4
Measured on a recurring basis | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	6,592.2	6,684.4
Measured on a recurring basis | U.S. government and government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	2,903.4	2,939.4
Measured on a recurring basis | Sovereign bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	70.4	64.1
Measured on a recurring basis | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	279.1	121.1
Measured on a recurring basis | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	153.7	182.0
Measured on a recurring basis | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	52.5	27.2
Measured on a recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	154.1	88.3
Assets, Fair Value Disclosure, Total	1,203.1	1,298.3
Measured on a recurring basis | Level 1 | Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	20.7	24.6
Measured on a recurring basis | Level 1 | Restricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,028.3	1,185.4
Measured on a recurring basis | Level 1 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | U.S. government and government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Sovereign bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,268.6	1,574.5
Assets, Fair Value Disclosure, Total	11,329.6	11,592.7
Measured on a recurring basis | Level 2 | Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0.0	0.0
Measured on a recurring basis | Level 2 | Restricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	9.7	0.0
Measured on a recurring basis | Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	6,592.2	6,684.4
Measured on a recurring basis | Level 2 | U.S. government and government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	2,903.4	2,939.4
Measured on a recurring basis | Level 2 | Sovereign bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	70.4	64.1
Measured on a recurring basis | Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	279.1	121.1
Measured on a recurring basis | Level 2 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	153.7	182.0
Measured on a recurring basis | Level 2 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	$ 52.5	$ 27.2