Consolidated Statements of Cash Flows - Balances per Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Balances per Consolidated Balance Sheets:
Cash and cash equivalents	$ 1,093	$ 981
Restricted cash	1,918	2,175
Total cash, cash equivalents and restricted cash	$ 3,011	$ 3,156	$ 2,422	$ 2,613

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. 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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Balance Type:	debit
Period Type:	instant