Condensed Consolidated Statements of Cash Flows Condensed Consolidated Statement of Cash Flows (Supplemental Disclosure) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 277	$ 146	$ 168
Restricted cash and restricted cash equivalents included in Other current assets	357	655	781
Restricted cash equivalents included in Other long-term assets	43	27	31
Cash, cash equivalents, restricted cash and restricted cash equivalents at end of period	$ 676	$ 829	$ 980	$ 1,017