Supplemental Cash Flow Information (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash paid for or (received from):
Cash and cash equivalents	$ 280	$ 224	$ 192
Restricted cash	89	89	89
Cash related to discontinued operations			282
Cash and Cash Equivalents Including Restricted Cash, at Carrying Value	368	313	563
Finance leases and other non-cash financing transactions	$ 46	$ 36	$ 41