Schedule I - Condensed Financial Information Of Parent Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Cash and Cash Equivalents Including Restricted Cash [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 16	$ 10
Restricted Cash and Cash Equivalents, Noncurrent	74	35
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	107	68	$ 52	$ 351
Parent Company
Schedule of Cash and Cash Equivalents Including Restricted Cash [Line Items]
Cash and Cash Equivalents, at Carrying Value	0	0
Restricted Cash and Cash Equivalents, Noncurrent	1	8
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 1	$ 8	$ 9	$ 8