Summary of Accounting Principles (Long-Term Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total Long Term Receivable	$ 1,397	$ 1,356
Percentage Long Term Receivables High Credit Risk	11.00%	13.00%
Financing Receivable, Reserve for Credit Losses and Exposure, Individually Evaluated For Impairment	$ 17	$ 17
Long-term Trade Accounts Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Long Term Receivable	973	926
Notes and Leases Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Long Term Receivable	$ 424	$ 430

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.

+ Details

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- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

The reserve for credit losses and exposure for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

No definition available.

+ Details

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Balance Type:	credit
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- Definition

The percentage of long-term receivables that are considered to bear high credit risk based upon the customer credit ratings.

+ References

No definition available.

+ Details

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- Details

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- Details

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