Supplemental Financial Information - Other Assets (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Other Assets [Abstract]
Derivative contracts		$ 60	$ 49
Intangible assets		296	296
Other		264	232
Other assets		620	577
Other Assets | Interest rate derivatives
Other Assets [Abstract]
Derivative contracts	[1]	$ 0	$ 2

[1] The net amounts of derivative assets and liabilities are reconciled to the individual line item amounts presented in the unaudited Condensed Consolidated Balance Sheet in Note 10.