Impairments - Fair Value Measurements, Nonrecurring (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 0	$ 95	$ 95	$ 95
Goodwill, Impairment Loss	95	0
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Long-lived assets, Fair Value		37
Long-lived assets, Impairment	$ 2	$ 6