Other Material Contingencies - Manhattan Steam Main Rupture (Details) $ in Millions	Sep. 30, 2018 USD ($)
Property Damage, Clean Up and Other Response Costs Related with Manhattan Steam Main Rupture
Loss Contingencies [Line Items]
Loss contingency	$ 10
Capital, Retirement and Other Costs Related with Manhattan Steam Main Rupture
Loss Contingencies [Line Items]
Loss contingency	$ 7

Amount of loss contingency liability.

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

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