Revenue Recognition - Summary of Disaggregation of Revenue by Major Sources (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation Of Revenue [Line Items]
Total sales	$ 528,096	$ 648,187
Home heating oil and propane
Disaggregation Of Revenue [Line Items]
Total sales	351,214	435,523
Other petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	97,336	134,406
Petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	448,550	569,929
Equipment installations
Disaggregation Of Revenue [Line Items]
Total sales	34,315	32,789
Equipment maintenance service contracts
Disaggregation Of Revenue [Line Items]
Total sales	28,916	28,716
Billable call services
Disaggregation Of Revenue [Line Items]
Total sales	16,315	16,753
Installations and services
Disaggregation Of Revenue [Line Items]
Total sales	$ 79,546	$ 78,258