Leases - Cash Flow Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Cash Flow, Lessee [Abstract]
Operating Cash Flows, Operating Leases	$ 30
Operating Cash Flows, Finance Leases	6
Financing Cash Flows, Finance Leases	20
Investing Cash Flows, Operating Leases	18
ROU Assets Obtained in Exchange for Lease Liability, Operating	58
ROU Assets Obtained in Exchange for Lease Liability, Finance	$ 8