Contingent Liabilities (Details) - USD ($) $ in Millions	Sep. 26, 2016	Sep. 30, 2016
Contingent Liabilities [Line Items]
Accrued environmental loss liabilities		$ 14.0
Gas Pipeline [Member]
Contingent Liabilities [Line Items]
Accrued environmental loss liabilities		7.0
Natural gas underground storage facilities [Member]
Contingent Liabilities [Line Items]
Accrued environmental loss liabilities		7.0
NGL And Petchem Services [Member] | Geismar Incident [Member]
Contingent Liabilities [Line Items]
Litigation Judgment or Settlement, Amount	$ 13.6
NGL And Petchem Services [Member] | General Liability Coverage [Member] | Geismar Incident [Member]
Contingent Liabilities [Line Items]
Aggregate Limit of Insurance		610.0
Insurance Deductibles		$ 2.0