Leases (Lease Cost and Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 90	$ 94
Short-term lease cost	1	1
Variable lease cost	34	37
Sublease income	(5)	(8)
Net lease cost	120	124
Operating cash outflows from operating leases	99	99
Right of use assets obtained in exchange for new operating lease liabilities	$ 51	$ 22
Real Estate Lease
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term	8 years 8 months 12 days	8 years 3 months 18 days
Weighted-average discount rate, percent	2.75%	2.93%