Long-Term Debt and Short-Term Borrowings - Short-Term Borrowings and Current Portion of Long-Term Debt (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Short-Term Borrowings and Current Portion of Long-Term Debt
Short-term borrowings and current portion of long-term debt	$ 1,307,000,000	$ 1,853,000,000
Commercial paper
Short-Term Borrowings and Current Portion of Long-Term Debt
Short-term borrowings and current portion of long-term debt	$ 0	$ 745,000,000

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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