Revenue Recognition - Summary of Disaggregation of Revenue by Major Sources (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Disaggregation Of Revenue [Line Items]
Total sales	$ 782,543	$ 604,115	$ 1,270,813	$ 977,435
Home heating oil and propane
Disaggregation Of Revenue [Line Items]
Total sales	593,475	466,401	899,198	707,213
Other petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	118,987	72,970	224,529	132,490
Petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	712,462	539,371	1,123,727	839,703
Equipment installations
Disaggregation Of Revenue [Line Items]
Total sales	26,965	22,865	60,034	52,925
Equipment maintenance service contracts
Disaggregation Of Revenue [Line Items]
Total sales	27,341	27,045	54,318	53,913
Billable call services
Disaggregation Of Revenue [Line Items]
Total sales	15,775	14,834	32,734	30,894
Installations and services
Disaggregation Of Revenue [Line Items]
Total sales	$ 70,081	$ 64,744	$ 147,086	$ 137,732