Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	$ 12,620.4	$ 10,018.2
Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	6,537.6	6,684.4
U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	5,082.3	2,939.4
Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	65.6	64.1
Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	505.1	121.1
Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	342.6	182.0
Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	87.2	27.2
Measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	1,018.5	1,662.8
Total assets	14,558.3	12,891.0
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration - CVRs	43.7
Measured on a recurring basis | Unrestricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	802.3	24.6
Measured on a recurring basis | Restricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	117.1	1,185.4
Measured on a recurring basis | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	6,537.6	6,684.4
Measured on a recurring basis | U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	5,082.3	2,939.4
Measured on a recurring basis | Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	65.6	64.1
Measured on a recurring basis | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	505.1	121.1
Measured on a recurring basis | Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	342.6	182.0
Measured on a recurring basis | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	87.2	27.2
Measured on a recurring basis | Level 1
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	119.9	88.3
Total assets	1,039.3	1,298.3
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration - CVRs	0.0
Measured on a recurring basis | Level 1 | Unrestricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	802.3	24.6
Measured on a recurring basis | Level 1 | Restricted
Assets, Fair Value Disclosure [Abstract]
Equity securities	117.1	1,185.4
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	898.6	1,574.5
Total assets	13,519.0	11,592.7
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration - CVRs	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	6,537.6	6,684.4
Measured on a recurring basis | Level 2 | U.S. government and government agency obligations
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	5,082.3	2,939.4
Measured on a recurring basis | Level 2 | Sovereign bonds
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	65.6	64.1
Measured on a recurring basis | Level 2 | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	505.1	121.1
Measured on a recurring basis | Level 2 | Certificates of deposit
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	342.6	182.0
Measured on a recurring basis | Level 2 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Available-for-sale debt securities	87.2	27.2
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 - CVRs	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