Revenue Recognition - Summary of Disaggregation of Revenue by Major Sources (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation Of Revenue [Line Items]
Total sales	$ 737,617	$ 782,543	$ 1,385,804	$ 1,270,813
Home heating oil and propane
Disaggregation Of Revenue [Line Items]
Total sales	566,457	593,475	1,001,980	899,198
Other petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	102,755	118,987	237,161	224,529
Petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	669,212	712,462	1,239,141	1,123,727
Equipment installations
Disaggregation Of Revenue [Line Items]
Total sales	25,208	26,965	57,997	60,034
Equipment maintenance service contracts
Disaggregation Of Revenue [Line Items]
Total sales	28,961	27,341	57,677	54,318
Billable call services
Disaggregation Of Revenue [Line Items]
Total sales	14,236	15,775	30,989	32,734
Installations and services
Disaggregation Of Revenue [Line Items]
Total sales	$ 68,405	$ 70,081	$ 146,663	$ 147,086