Comprehensive (Loss) Income (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended	6 Months Ended		12 Months Ended
	Mar. 27, 2019	Nov. 30, 2019	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2019	Jun. 30, 2020	Nov. 05, 2019	Dec. 31, 2018
Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Derivative Notional Amount Agreement Terminated	$ 479	$ 171	$ 171	$ 479
Derivative, Notional Amount	650		550	171	$ 550	$ 550	$ 550	$ 650
Amount Received From Terminated Interest Rate Swap	$ 12	$ 0		12	12
Derivative, Fair Value, Net			12	$ 12	12
Interest rate swap, remaining unamortized amount						$ 8
Interest Rate Swap Contracts II [Member]
Derivative [Line Items]
Derivative Notional Amount Agreement Terminated					171
Derivative, Notional Amount			$ 650		650
Amount Received From Terminated Interest Rate Swap					$ 1