Leases - Supplemental Cash Flow (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 6
Operating cash flows from financing leases	0
Financing cash flows from finance leases	0
Right-of-use assets obtained in exchange for new operating lease liabilities	67
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 1