Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Available-for-sale debt securities:
Available-for-sale debt securities	$ 9,712.1	$ 8,397.2
Corporate bonds
Available-for-sale debt securities:
Available-for-sale debt securities	7,578.2	7,487.7
U.S. government and government agency obligations
Available-for-sale debt securities:
Available-for-sale debt securities	1,046.0	108.5
Sovereign bonds
Available-for-sale debt securities:
Available-for-sale debt securities	44.1	64.4
Commercial paper
Available-for-sale debt securities:
Available-for-sale debt securities	667.8	439.6
Certificates of deposit
Available-for-sale debt securities:
Available-for-sale debt securities	336.6	255.1
Asset-backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	39.4	41.9
Measured on a recurring basis
Available-for-sale debt securities:
Total marketable securities	10,587.2	9,647.1
Measured on a recurring basis | Unrestricted
Available-for-sale debt securities:
Equity securities	35.2	58.4
Measured on a recurring basis | Restricted
Available-for-sale debt securities:
Equity securities	839.9	1,191.5
Measured on a recurring basis | Corporate bonds
Available-for-sale debt securities:
Available-for-sale debt securities	7,578.2	7,487.7
Measured on a recurring basis | U.S. government and government agency obligations
Available-for-sale debt securities:
Available-for-sale debt securities	1,046.0	108.5
Measured on a recurring basis | Sovereign bonds
Available-for-sale debt securities:
Available-for-sale debt securities	44.1	64.4
Measured on a recurring basis | Commercial paper
Available-for-sale debt securities:
Available-for-sale debt securities	667.8	439.6
Measured on a recurring basis | Certificates of deposit
Available-for-sale debt securities:
Available-for-sale debt securities	336.6	255.1
Measured on a recurring basis | Asset-backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	39.4	41.9
Measured on a recurring basis | Level 1
Available-for-sale debt securities:
Total marketable securities	875.1	1,249.9
Measured on a recurring basis | Level 1 | Unrestricted
Available-for-sale debt securities:
Equity securities	35.2	58.4
Measured on a recurring basis | Level 1 | Restricted
Available-for-sale debt securities:
Equity securities	839.9	1,191.5
Measured on a recurring basis | Level 1 | Corporate bonds
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | U.S. government and government agency obligations
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Sovereign bonds
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Commercial paper
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Certificates of deposit
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 1 | Asset-backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Measured on a recurring basis | Level 2
Available-for-sale debt securities:
Total marketable securities	9,712.1	8,397.2
Measured on a recurring basis | Level 2 | Unrestricted
Available-for-sale debt securities:
Equity securities	0.0	0.0
Measured on a recurring basis | Level 2 | Restricted
Available-for-sale debt securities:
Equity securities	0.0	0.0
Measured on a recurring basis | Level 2 | Corporate bonds
Available-for-sale debt securities:
Available-for-sale debt securities	7,578.2	7,487.7
Measured on a recurring basis | Level 2 | U.S. government and government agency obligations
Available-for-sale debt securities:
Available-for-sale debt securities	1,046.0	108.5
Measured on a recurring basis | Level 2 | Sovereign bonds
Available-for-sale debt securities:
Available-for-sale debt securities	44.1	64.4
Measured on a recurring basis | Level 2 | Commercial paper
Available-for-sale debt securities:
Available-for-sale debt securities	667.8	439.6
Measured on a recurring basis | Level 2 | Certificates of deposit
Available-for-sale debt securities:
Available-for-sale debt securities	336.6	255.1
Measured on a recurring basis | Level 2 | Asset-backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	$ 39.4	$ 41.9