Debt (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Short Term Debt Line Items
Outstanding Balance	$ 1,308	$ 2,993
Year-End Stated Rate on Debt	1.51%	1.13%
Commercial Paper [Member] \| Short Term Debt [Member]
Short Term Debt Line Items
Outstanding Balance	$ 1,168	$ 2,993
Year-End Stated Rate on Debt	1.54%	1.13%
Other Short Term Borrowings [Member] \| Short Term Debt [Member]
Short Term Debt Line Items
Outstanding Balance	$ 140	$ 0
Year-End Stated Rate on Debt	1.27%	0.00%

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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(19)(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_ShortTermBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant