Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jul. 31, 2021	Jun. 30, 2021
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 390	$ 341
Lease liabilities reduced by cash paid	385	276
Right-of-use assets obtained in exchange for operating lease liability	177	349
Lease liability for leases commenced	177	$ 349
Operating lease not yet commenced, liability	$ 28
Weighted average remaining lease term	21 years 1 month 6 days	9 years 3 months 18 days		9 years 2 months 12 days
Weighted average discount rate for operating leases	5.70%	3.10%
Circle Health
Lessee, Lease, Description [Line Items]
Right-of-use assets obtained in exchange for operating lease liability	$ 2,380
Percentage of voting interests acquired			60.00%
Increase in operating lease liability	$ 2,380
Weighted average remaining lease term			28 years 2 months 12 days
Minimum
Lessee, Lease, Description [Line Items]
Operating lease not yet commenced, term	5 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease not yet commenced, term	9 years