Leases - Supplemental Cash Flow Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 4	$ 19
Operating cash flows from finance leases	1	4
Finance cash flows from finance leases	12	21
Operating leases	47	73
Finance leases	$ 0	$ 2
Operating leases, weighted-average remaining lease terms	8 years 4 months 20 days	8 years 4 months 20 days
Finance leases, weighted-average remaining lease terms	4 years 7 months 28 days	4 years 7 months 28 days
Operating leases, weighted-average discount rate	4.76%	4.76%
Finance leases, weighted-average discount rate	3.45%	3.45%
Operating lease assets, net of accumulated amortization of $17 million	$ 200	$ 200
Finance lease assets, net of accumulated amortization of $91 million	76	76
Leased Asset	276	276
Operating liability, current	34	34
Finance liability, current	16	16
Operating liability, noncurrent	212	212
Finance liability, noncurrent	47	47
Total leased liabilities	309	309
Operating lease assets, accumulated amortization	17	17
Financing lease, accumulated amortization	$ 91	$ 91