Other Commitments and Contingencies - Additional Information (Detail) $ in Thousands, gal in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) dekatherm / d gal	Dec. 31, 2014 USD ($) dekatherm / d
Other Contingencies And Commitments [Line Items]
Number of years to purchase propane under contract	6 years
Number Of Years Remaining To Purchase Propane Under Contract	3 years 4 months
Annual Estimate Of Volume Of Propane To Be Purchased | gal	6.5
Total liabilities to tangible net worth minimum times	3.75
Fixed charge coverage ratio minimum times	1.5
Time to cure ratio	30 days
Funds from operations interest coverage ratio minimum times	2
Total debt to capital maximum	0.65
Document Period End Date	Sep. 30, 2015
Maximum authorized liability under such guarantees and letters of credit	$ 50,000
Aggregate guaranteed amount	36,100
Liability for Uncertain Tax Positions, Noncurrent	100	$ 100
Unrecognized Tax Benefits	$ 404	$ 724
Purchase Commitment Minimum Volume | dekatherm / d	9,982
Purchase Commitment Maximum Volume | dekatherm / d		13,423
September 12, 2016 [Member]
Other Contingencies And Commitments [Line Items]
Draws on letters of credit	$ 1,000
October 31,, 2016 [Member]
Other Contingencies And Commitments [Line Items]
Draws on letters of credit	1,200
June 1, 2016 [Member]
Other Contingencies And Commitments [Line Items]
Draws on letters of credit	24
March 31, 2016 [Member]
Other Contingencies And Commitments [Line Items]
Draws on letters of credit	1,000
TETLP [Member]
Other Contingencies And Commitments [Line Items]
Draws on letters of credit	$ 2,300