Financial Instruments (Narrative) (Details) - Fair Value, Inputs, Level 1 [Member] - USD ($) $ in Millions |
Sep. 30, 2017 |
Dec. 31, 2016 |
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| Money Market Funds [Member] | ||
| Schedule of Investments [Line Items] | ||
| Investment in money market fund used as collateral | $ 2 | $ 2 |
| Mutual Funds [Member] | ||
| Schedule of Investments [Line Items] | ||
| Restricted investments | $ 17 | $ 15 |
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- Definition Amount of cash equivalents restricted as to withdrawal or usage. 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. No definition available.
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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