Consolidated Statements of Cash Flows Consolidated Statement of Cash Flows (Supplemental Disclosure) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 829,000,000	$ 1,017,000,000	$ 487,000,000	$ 400,000,000
Restricted Cash Equivalents, Noncurrent	27,000,000	26,000,000	22,000,000
Restricted Cash and Cash Equivalents, Current	655,000,000	803,000,000	269,000,000
Cash and Cash Equivalents, at Carrying Value	$ 146,000,000	$ 188,000,000	$ 196,000,000