Long-Term Borrowings - Additional Information (Details) - USD ($)			3 Months Ended		6 Months Ended
	Feb. 14, 2017	Mar. 03, 2016	Mar. 25, 2017	Mar. 26, 2016	Mar. 25, 2017	Mar. 26, 2016	Sep. 24, 2016		Aug. 06, 2013	Aug. 02, 2013
Debt Instrument [Line Items]
Ownership interest in Suburban Energy Finance Corp (in hundredths)			100.00%		100.00%
Loss on debt extinguishment			$ 1,567,000	$ 292,000	$ 1,567,000	$ 292,000
Long-term borrowings			1,238,355,000		$ 1,238,355,000		$ 1,224,502,000	[1]
Consolidated interest coverage ratio, minimum					2.5
Total consolidated leverage ratio, maximum					5.5
Senior secured unconsolidated leverage ratio maximum					3.0
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, 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			129,845,000		129,845,000
Long-term debt maturities, 2021 and thereafter			1,125,000,000		1,125,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Standby letters of credit issued under the Revolving Credit Facility			$ 43,256,000		$ 43,256,000
Amended Credit Agreement Due 2021 [Member]
Debt Instrument [Line Items]
Weighted average interest rate (in hundredths)			3.50%		3.50%
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%
7.375% 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
Debt instrument repurchase amount									$ 23,863,000	$ 133,400,000
Loss on debt extinguishment	$ 1,567,000
Redemption premium and related fees	15,078,000
Write-off unamortized debt origination costs	2,272,000
Write-off unamortized premium	$ (15,783,000)
Long-term borrowings			$ 0		$ 0		$ 363,172,000	[1]
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	[1]
7.5% Senior Notes due October 1, 2018 [Member]
Debt Instrument [Line Items]
Stated interest rate (in hundredths)			7.50%		7.50%
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	[1]
7.375% Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Stated interest rate (in hundredths)			7.375%		7.375%
5.875% Senior Notes due March 1, 2027 [Member]
Debt Instrument [Line Items]
Date public offering completed					Feb. 14, 2017
Aggregate principal amount			$ 350,000,000		$ 350,000,000
Stated interest rate (in hundredths)			5.875%		5.875%		5.875%
Maturity date					Mar. 01, 2027
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			$ 350,000,000		$ 350,000,000		$ 0	[1]
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term borrowings			$ 129,845,000		$ 129,845,000		$ 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

[1] Long-term borrowings as of September 24, 2016 reflect the retrospective impact from the adoption of new accounting guidance regarding the balance sheet classification of debt issuance costs (See Note 2).