Leases - Components of Operating Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 87	$ 127	$ 136
Variable lease cost	48	59	63
Short-term lease cost	0	0	4
Sublease income	(43)	(54)	(60)
Total operating lease costs, net	92	132	143
Cash paid for amounts included in the measurement of operating lease liabilities	129	135	126
ROU assets recognized for new operating lease liabilities	$ 0	$ 24	$ 132