Other Commitments and Contingencies - Additional Information (Detail) $ in Thousands, gal in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) gal
Subsequent Event [Line Items]
Intercompany Agreements, Description	3
Annual Estimate Of Volume Of Propane To Be Purchased | gal	1.2
Debt Service Coverage Ratio	1.25
Time to cure ratio	5 days
Ratio based on average number of prior quarters	6
Funds from operations interest coverage ratio minimum times	2
Total debt to capital maximum	65
Number Of Years to Collect Benefits	20 years
Total purchase obligations for 2018	$ 158,500
Total purchase obligations for 2019 - 2020	74,970
Total purchase obligations for 2021 - 2022	42,279
Total purchase obligations thereafter	129,019
Maximum authorized liability under such guarantees and letters of credit	95,000
Aggregate guaranteed amount	76,500
Amount of letter of credit to our current primary insurance company	$ 7,000