Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions				1 Months Ended							2 Months Ended	3 Months Ended				12 Months Ended	84 Months Ended	97 Months Ended
		Nov. 16, 2020	Oct. 27, 2020	Nov. 30, 2020		Oct. 31, 2020		Sep. 30, 2020	Aug. 31, 2020	Jul. 31, 2020	Nov. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Jul. 31, 2020
Repurchase Plan
Subsequent Event [Line Items]
Company's common units repurchased and retired								255	159	725		1,139	1,155	782	1,281	4,357	13,340	14,400
Average price paid per unit	[1]							$ 9.63	$ 9.33	$ 8.97		$ 9.17	$ 8.15	$ 8.33	$ 9.42	$ 8.82	$ 8.08
Subsequent Event | Propane Assets
Subsequent Event [Line Items]
Proceeds from sale of propane assets			$ 7.0
Subsequent Event | Repurchase Plan
Subsequent Event [Line Items]
Company's common units repurchased and retired				1,553		308					500
Average price paid per unit				$ 9.83	[1]	$ 9.64	[1]				$ 9.65
Subsequent Event | Unit Purchase Agreement | Moab Partners, L.P.
Subsequent Event [Line Items]
Company's common units repurchased		1,400
Aggregate consideration paid for common units purchased		$ 13.8
Subsequent Event | Dividend Declared
Subsequent Event [Line Items]
Distribution declared						0.1325
Partners capital projected distribution amount on annualized basis						0.53
Minimum dividend distribution per unit						$ 0.0675
Amount to paid to common unit holders						$ 5.7
Amount to paid to the General Partner						0.2
Incentive distribution to the General Partner						0.2
Incentive distributions to management						$ 0.2
Dividend paid date						Nov. 10, 2020
Dividend record date						Nov. 02, 2020

[1] Amounts include repurchase costs.