Revenue Recognition - Summary of Disaggregation of Revenue by Major Sources (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation Of Revenue [Line Items]
Total sales	$ 439,101	$ 283,100	$ 1,709,914	$ 1,260,535
Home heating oil and propane
Disaggregation Of Revenue [Line Items]
Total sales	189,262	111,451	1,088,460	818,664
Other petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	168,974	93,594	393,503	226,084
Petroleum products
Disaggregation Of Revenue [Line Items]
Total sales	358,236	205,045	1,481,963	1,044,748
Equipment installations
Disaggregation Of Revenue [Line Items]
Total sales	30,360	28,525	90,394	81,450
Equipment maintenance service contracts
Disaggregation Of Revenue [Line Items]
Total sales	33,185	32,196	87,503	86,109
Billable call services
Disaggregation Of Revenue [Line Items]
Total sales	17,320	17,334	50,054	48,228
Installations and services
Disaggregation Of Revenue [Line Items]
Total sales	$ 80,865	$ 78,055	$ 227,951	$ 215,787