Leases (Supplemental Information) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 11
Right-of use assets obtained in exchange for new operating liabilities	3
Right-of-use asset balance	100
Lease liability balance: (in millions)
Short-term operating leases	38
Long-term operating leases	62
Total operating leases	$ 100
Weighted average remaining lease term	4 years 1 month 6 days
Weighted average discount rate	5.86%