Leases - Lease activity (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating leases	$ 11	$ 22
Short-term leases	1	1
Total lease expense	$ 12	23
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows		24
Right-of-use assets obtained in exchange for new lease liabilities		$ 8
Weighted-average remaining lease term (in years)	5 years 9 months 18 days	5 years 9 months 18 days
Weighted-average discount rate (percent)	4.10%	4.10%