Partnership's Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Long-term debt, carrying Amount	$ 75,717	$ 91,641
Current maturities of long-term debt, carrying Amount	10,000	16,200
Long-term portion of debt, Carrying Amount	65,717	75,441
Long-term debt, fair value	76,300	92,500
Current maturities of long-term debt, fair value	10,000	16,200
Long-term portion of debt, fair value	66,300	76,300
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt, carrying Amount
Long-term debt, fair value
Term Loan
Debt Instrument [Line Items]
Long-term debt, carrying Amount	75,717	91,641
Long-term debt, fair value	$ 76,300	$ 92,500