Commitments and Contingencies, Non-Cancelable Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	$ 115
2020	134
2021	82
2022	73
2023	65
Thereafter	506
Total minimum payments required	975
Sublease rentals under non-cancelable leases	(7)
Net minimum payments required	968
Rent expense, net of sublease income	105	$ 103	$ 97
Sublease rental income	2	$ 1	$ 2
Real Estate [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	111
2020	132
2021	81
2022	73
2023	65
Thereafter	506
Total minimum payments required	968
Sublease rentals under non-cancelable leases	(7)
Net minimum payments required	961
Equipment [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	4
2020	2
2021	1
2022	0
2023	0
Thereafter	0
Total minimum payments required	7
Sublease rentals under non-cancelable leases	0
Net minimum payments required	$ 7