Summary of Accounting Principles (Long-Term Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total Long Term Receivable	$ 527	$ 1,397
Financing Receivable, Reserve for Credit Losses and Exposure, Individually Evaluated For Impairment	16	17
Long Term Receivables High Credit Risk	150	170
Long-term Trade Accounts Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Long Term Receivable	269	973
Notes and Leases Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Long Term Receivable	$ 258	$ 424

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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