Segment Information - Disclosure by Reportable Segment and Reconciliation of Total Operating Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Sep. 26, 2020
Revenues [Abstract]
Total revenues	$ 305,191	$ 333,878
Operating income (loss):
Total operating income (loss)	57,686	59,854
Reconciliation to net income:
Interest expense, net	18,135	19,072
Other, net	1,078	978
Provision for (benefit from) income taxes	496	(359)
Net income	37,977	40,163
Depreciation and amortization [Abstract]
Total depreciation and amortization	28,017	29,274
Assets [Abstract]
Total assets	2,110,271		$ 2,047,253
Operating/Reportable Segments [Member] | Propane [Member]
Revenues [Abstract]
Total revenues	268,624	285,425
Operating income (loss):
Total operating income (loss)	83,604	86,122
Depreciation and amortization [Abstract]
Total depreciation and amortization	25,691	26,980
Assets [Abstract]
Total assets	1,981,099		1,934,960
Operating/Reportable Segments [Member] | Fuel Oil and Refined Fuels [Member]
Revenues [Abstract]
Total revenues	15,750	25,891
Operating income (loss):
Total operating income (loss)	2,625	2,728
Depreciation and amortization [Abstract]
Total depreciation and amortization	400	507
Assets [Abstract]
Total assets	50,143		47,063
Operating/Reportable Segments [Member] | Natural Gas and Electricity [Member]
Revenues [Abstract]
Total revenues	6,876	8,721
Operating income (loss):
Total operating income (loss)	1,959	2,229
Depreciation and amortization [Abstract]
Total depreciation and amortization	6	0
Assets [Abstract]
Total assets	11,935		10,594
Operating/Reportable Segments [Member] | All Other [Member]
Revenues [Abstract]
Total revenues	13,941	13,841
Operating income (loss):
Total operating income (loss)	(5,061)	(5,387)
Depreciation and amortization [Abstract]
Total depreciation and amortization	47	47
Assets [Abstract]
Total assets	19,639		18,733
Operating/Reportable Segments [Member] | Corporate [Member]
Operating income (loss):
Total operating income (loss)	(25,441)	(25,838)
Depreciation and amortization [Abstract]
Total depreciation and amortization	1,873	$ 1,740
Assets [Abstract]
Total assets	$ 47,455		$ 35,903