Goodwill and Long-Lived Assets - Amortization Expense (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense three months ended 2019	$ 21	$ 42
Amortization expense remainder of 2019 (estimated)	43	43
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	68	68
2021	59	59
2022	55	55
2023	52	52
2024	$ 47	$ 47