CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of cash, cash equivalents and restricted cash and cash equivalents at end of period:
Cash and cash equivalents	$ 3,561	$ 61	$ 22
Restricted cash and cash equivalents included in other current assets	15	49	70
Restricted cash and cash equivalents included in restricted trust and escrow accounts	71	73	201
Cash, cash equivalents and restricted cash and cash equivalents at end of period	$ 3,647	$ 183	$ 293

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Name:	us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant