Leases - Other Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Other information
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases	$ 14	$ 14	$ 43	$ 40
Right-of-use assets obtained in exchange for lease liabilities: Operating leases	$ 18	$ 24	$ 57	$ 45
Weighted average remaining lease term (years): Operating leases	6 years 8 months 12 days		6 years 8 months 12 days		5 years 6 months
Weighted average discount rate: Operating leases	4.20%		4.20%		4.90%