Indebtedness (Credit Facilities) (Details) - USD ($) $ in Billions	Dec. 31, 2019	Jan. 28, 2019
Line of Credit Facility [Line Items]
Committed Credit Facilities	$ 8.0
Commercial Paper	0.0
364-day revolving credit, expiring February 4, 2020 [Member]
Line of Credit Facility [Line Items]
Committed Credit Facilities	2.0	$ 2.0
Multi-year revolving credit, expiring February 28, 2021 [Member]
Line of Credit Facility [Line Items]
Committed Credit Facilities	2.5
Multi-year revolving credit, expiring October 1, 2022 [Member]
Line of Credit Facility [Line Items]
Committed Credit Facilities	$ 3.5

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: 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)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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