Leases (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease expense		$ 11	$ 9
Variable lease payments not included in the measurement of lease liabilities		5	4
Short-term lease payments not included in the measurement of lease liabilities		2	3
Cash paid for amounts included in the measurement of lease liabilities		11	9
Lease obligations obtained in exchange for right-of-use assets (non-cash)		4	$ 176
Operating lease right of use assets		182		$ 189
Operating lease liabilities - current (in Other current liabilities)		33		35
Operating lease liabilities - noncurrent		159		164
Total operating lease liabilities		$ 192		$ 199
Weighted-average remaining lease term—operating leases (years)		7 years 18 days		7 years 1 month 13 days
Weighted-average discount rate—operating leases		3.34%		3.76%
2020	[1]	$ 31
2021		37
2022		33
2023		27
2024		23
After 2024		68
Total Lease Payments		219
Less: Imputed Interest		$ (27)
Minimum
Lessee, Lease, Description [Line Items]
Remaining terms		1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining terms		15 years

[1] 2020 excludes the three months ended March 31, 2020