Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	$ 14,115.0	$ 12,533.9
Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	7,401.1	6,398.0
U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	5,273.4	4,833.4
Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	59.0	57.2
Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	866.9	636.8
Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	389.9	521.4
Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	124.7	87.1
Measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	1,056.4	928.1
Total assets	15,952.7	14,439.4
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	59.0	43.7
Measured on a recurring basis | Unrestricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	679.4	864.5
Measured on a recurring basis | Restricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	101.9	112.9
Measured on a recurring basis | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	7,401.1	6,398.0
Measured on a recurring basis | U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	5,273.4	4,833.4
Measured on a recurring basis | Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	59.0	57.2
Measured on a recurring basis | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	866.9	636.8
Measured on a recurring basis | Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	389.9	521.4
Measured on a recurring basis | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	124.7	87.1
Measured on a recurring basis | Level 1
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	125.8	6.4
Total assets	907.1	983.8
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0.0	0.0
Measured on a recurring basis | Level 1 | Unrestricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	679.4	864.5
Measured on a recurring basis | Level 1 | Restricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	101.9	112.9
Measured on a recurring basis | Level 1 | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 2
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	930.6	921.7
Total assets	15,045.6	13,455.6
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0.0	0.0
Measured on a recurring basis | Level 2 | Unrestricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	0.0	0.0
Measured on a recurring basis | Level 2 | Restricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	0.0	0.0
Measured on a recurring basis | Level 2 | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	7,401.1	6,398.0
Measured on a recurring basis | Level 2 | U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	5,273.4	4,833.4
Measured on a recurring basis | Level 2 | Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	59.0	57.2
Measured on a recurring basis | Level 2 | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	866.9	636.8
Measured on a recurring basis | Level 2 | Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	389.9	521.4
Measured on a recurring basis | Level 2 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	124.7	87.1
Measured on a recurring basis | Level 3
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	0.0	0.0
Total assets	0.0	0.0
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	59.0	43.7
Measured on a recurring basis | Level 3 | Unrestricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	0.0	0.0
Measured on a recurring basis | Level 3 | Restricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	0.0	0.0
Measured on a recurring basis | Level 3 | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 3 | U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 3 | Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 3 | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 3 | Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 3 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	$ 0.0	$ 0.0