Long-Term Borrowings - Additional Information (Details) - USD ($)				3 Months Ended		9 Months Ended
	Mar. 03, 2016	Feb. 25, 2015	May 27, 2014	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015	Sep. 26, 2015	Aug. 06, 2013	Aug. 02, 2013	Aug. 01, 2012
Debt Instrument [Line Items]
Ownership interest in Suburban Energy Finance Corp (in hundredths)				100.00%		100.00%
Loss on debt extinguishment				$ 0	$ 0	$ 292,000	$ 15,072,000
Long-term borrowings				1,238,925,000		$ 1,238,925,000		$ 1,241,107,000
Consolidated interest coverage ratio, minimum						2.5
Total consolidated leverage ratio, maximum						5.5
Margin over basis rate (in hundredths)						1.00%
Notional Amount				100,000,000		$ 100,000,000
Consolidated fixed charge coverage ratio, minimum						1.75
Long-term debt maturities, 2016				0		$ 0
Long-term debt maturities, 2017				0		0
Long-term debt maturities, 2018				0		0
Long-term debt maturities, 2019				0		0
Long-term debt maturities, 2020				0		0
Long-term debt maturities, 2021 and thereafter				1,221,180,000		1,221,180,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Standby letters of credit issued under the Revolving Credit Facility				43,256,000		43,256,000
Existing borrowings under previous credit agreement				$ 356,744,000		$ 356,744,000
Amended Credit Agreement Due 2021 [Member]
Debt Instrument [Line Items]
Weighted average interest rate (in hundredths)				3.10%		3.10%
Amended Credit Agreement Due 2021 [Member] | Federal Funds Rate [Member]
Debt Instrument [Line Items]
Description of applicable interest rate on borrowings						Federal Funds Rate
Margin over basis rate (in hundredths)						0.50%
Amended Credit Agreement Due 2021 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Description of applicable interest rate on borrowings						LIBOR
Margin over basis rate (in hundredths)						1.00%
Amended Credit Agreement Due 2017 [Member]
Debt Instrument [Line Items]
Effective date						Jun. 25, 2013
Termination date						Jan. 05, 2017
Fixed interest rate (in hundredths)				1.63%		1.63%
7.5% Senior Notes due October 1, 2018 [Member]
Debt Instrument [Line Items]
Date public offering completed						Aug. 01, 2012
Aggregate principal amount				$ 496,557,000		$ 496,557,000
Stated interest rate (in hundredths)				7.50%		7.50%
Maturity date						Oct. 01, 2018
Fair value of debt at acquisition date (in hundredths)											106.875%
Loss on debt extinguishment			$ 11,589,000
Redemption premium and related fees			31,633,000
Write-off unamortized debt origination costs			5,230,000
Write-off unamortized premium			$ (25,274,000)
7.375% Senior Notes due August 1, 2021 [Member]
Debt Instrument [Line Items]
Date public offering completed						Aug. 01, 2012
Aggregate principal amount				$ 503,443,000		$ 503,443,000
Stated interest rate (in hundredths)				7.375%		7.375%		7.375%
Maturity date						Aug. 01, 2021
Fair value of debt at acquisition date (in hundredths)											108.125%
Debt instrument repurchase amount									$ 23,863,000	$ 133,400,000
Percentage of the principal amount repurchase offer under change of control provision (in hundredths)				101.00%		101.00%
Repurchase of debt due to decline in rating after consummation of change of control, period						90 days
Long-term borrowings				$ 363,925,000		$ 363,925,000		$ 366,107,000
7.375% Senior Notes due March 15, 2020 [Member]
Debt Instrument [Line Items]
Date public offering completed						Mar. 23, 2010
Aggregate principal amount				$ 250,000,000		$ 250,000,000
Stated interest rate (in hundredths)				7.375%		7.375%
Maturity date						Mar. 15, 2020
Loss on debt extinguishment		$ 15,072,000
Redemption premium and related fees		11,124,000
Write-off unamortized debt origination costs		2,855,000
Percentage of principal amount at which debt was issued (in hundredths)				99.136%		99.136%
Write-off unamortized discount		$ 1,093,000
5.5% Senior Notes due June 1, 2024 [Member]
Debt Instrument [Line Items]
Date public offering completed						May 27, 2014
Aggregate principal amount				$ 525,000,000		$ 525,000,000
Stated interest rate (in hundredths)				5.50%		5.50%		5.50%
Maturity date						Jun. 01, 2024
Percentage of principal amount at which debt was issued (in hundredths)				100.00%		100.00%
Percentage of the principal amount repurchase offer under change of control provision (in hundredths)				101.00%		101.00%
Repurchase of debt due to decline in rating after consummation of change of control, period						90 days
Long-term borrowings				$ 525,000,000		$ 525,000,000		$ 525,000,000
5.75% Senior Notes due March 1, 2025 [Member]
Debt Instrument [Line Items]
Date public offering completed						Feb. 25, 2015
Aggregate principal amount				$ 250,000,000		$ 250,000,000
Stated interest rate (in hundredths)				5.75%		5.75%		5.75%
Maturity date						Mar. 01, 2025
Percentage of principal amount at which debt was issued (in hundredths)				100.00%		100.00%
Percentage of the principal amount repurchase offer under change of control provision (in hundredths)				101.00%		101.00%
Repurchase of debt due to decline in rating after consummation of change of control, period						90 days
Long-term borrowings				$ 250,000,000		$ 250,000,000		$ 250,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit Facility, maximum amount	$ 500,000,000
Long-term borrowings				$ 100,000,000		100,000,000		$ 100,000,000
Revolving Credit Facility [Member] | Amended Credit Agreement Due 2021 [Member]
Debt Instrument [Line Items]
Write-off unamortized debt origination costs						$ 292,000
Credit Facility, maximum amount	$ 500,000,000
Revolving credit facility, term	5 years