Unit-Based Compensation Arrangements - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Aug. 06, 2013	Mar. 31, 2018	Mar. 25, 2017	Mar. 31, 2018	Mar. 25, 2017	Sep. 30, 2017
Distribution Equivalent Rights Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense		$ 201	$ 435	$ 408	$ 435
Distribution Equivalent Rights Plan, terms				On January 17, 2017, the Partnership adopted the Distribution Equivalent Rights Plan (the “DER Plan”), which gives the Compensation Committee of the Partnership’s Board of Supervisors discretion to award distribution equivalent rights (“DERs”) to executive officers of the Partnership. Once awarded, DERs entitle the grantee to a cash payment each time the Board of Supervisors declares a cash distribution on the Partnership’s Common Units, which cash payment will be equal to an amount calculated by multiplying the number of unvested restricted units which are held by the grantee on the record date of the distribution, by the amount of the declared distribution per Common Unit.
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total number of Common Units authorized for issuance (in units)		2,400,000		2,400,000
Restricted Unit Plans, terms of award				In accordance with an August 6, 2013 amendment to the Restricted Unit Plan, unless otherwise stipulated by the Compensation Committee of the Partnership’s Board of Supervisors on or before the grant date, all restricted unit awards granted after the date of the amendment will vest 33.33% on each of the first three anniversaries of the award grant date. Prior to the August 6, 2013 amendment, unless otherwise stipulated by the Compensation Committee of the Partnership’s Board of Supervisors on or before the grant date, restricted units issued under the Restricted Unit Plan vest over time with 25% of the Common Units vesting at the end of each of the third and fourth anniversaries of the grant date and the remaining 50% of the Common Units vesting at the end of the fifth anniversary of the grant date. The Restricted Unit Plan participants are not eligible to receive quarterly distributions on, or vote, their respective restricted units until vested. Restricted units cannot be sold or transferred prior to vesting. The value of the restricted unit is established by the market price of the Common Unit on the date of grant, net of estimated future distributions during the vesting period. Restricted units are subject to forfeiture in certain circumstances as defined in the Restricted Unit Plan.
Number of restricted units awarded				424,431
Aggregate grant date fair value of restricted units awarded				$ 8,285
Unrecognized compensation cost		$ 6,062		$ 6,062
Weighted-average recognition period of compensation cost				1 year 1 month 6 days
Compensation expense		2,498	1,962	$ 5,147	4,837
Long-Term Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Long-Term Incentive Plan, terms of award				The LTIP is a non-qualified, unfunded, long-term incentive plan for officers and key employees that provides for payment, in the form of cash, of an award of equity-based compensation at the end of a three-year performance period.
Measurement period of average distribution coverage ratio	3 years
Compensation expense		492	$ (489)	$ 2,124	$ (1,476)
Liability included within accrued employment and benefit costs (or other liabilities, as applicable) related to estimated future payments under the LTIP		$ 3,760		$ 3,760		$ 1,637