Commitments and Contingencies (Environmental) (Details) $ in Millions	Mar. 31, 2018 USD ($) Superfund_Sites	Dec. 31, 2017 USD ($)
Accrual for Environmental Loss Contingencies Disclosure [Abstract]
Accrual for Environmental Loss Contingencies	$ 45	$ 48
Superfund Sites [Member]
Accrual for Environmental Loss Contingencies Disclosure [Abstract]
Number Of Superfund Sites \| Superfund_Sites	8
Accrual for Environmental Loss Contingencies, Gross	$ 8

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

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