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Commitments and Contingencies Commitments and Contingencies (Details)
$ in Millions
3 Months Ended
Apr. 03, 2018
Mar. 31, 2018
USD ($)
MMcf
Loss Contingencies [Line Items]    
Self-Insured Retention Expense | $   $ 1.0
Subsequent Event [Member]    
Subsequent Event [Line Items]    
Subsequent Event, Description
On April 3, 2018, we filed formula rate mechanisms in our Mid-Tex and West Texas service areas, seeking increases in operating income
 
Pending Litigation [Member]    
Loss Contingencies [Line Items]    
Loss Contingency, Damages Sought, Value | $   $ 1.0
Loss Contingency, Lawsuit Filing Date   March 29, 2018
Inventories Under Indexed Contracts [Member] | Distribution Segment [Member]    
Long-term Purchase Commitment [Line Items]    
Long Term Purchase Commitment Minimum Quantity Required Within One Year | MMcf   55,000
Long Term Purchase Commitment Minimum Quantity Required One To Three Years | MMcf   64,700