Leases Lessee Disclosure - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Disclosure of Cash Flow Information
Operating cash flows from operating leases	$ 153
Operating cash flows from finance leases	1
Financing cash flows from finance leases	14
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	153
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 18	$ 20	$ 18