Comprehensive (Loss) Income (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Nov. 30, 2019	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Nov. 05, 2019	Dec. 31, 2018
Interest Rate Swap Contract [Member]
Derivative [Line Items]
Derivative Notional Amount Agreement Terminated	$ 171	$ 171	$ 4	$ 479
Derivative, Notional Amount		550	546	171	$ 550	$ 550	$ 650
Amount Received From Terminated Interest Rate Swap	$ 0			12	12
Derivative, Fair Value, Net		12		$ 12	12
Interest rate swap, remaining unamortized amount			$ 7
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