Partnership's Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Long-term debt, carrying Amount	$ 92,500	$ 100,000
Current maturities of long-term debt, carrying Amount	16,200	10,000
Long-term portion of debt, Carrying Amount	76,300	90,000
Long-term debt, fair value	92,500	100,000
Current maturities of long-term debt, fair value	16,200	10,000
Long-term portion of debt, fair value	76,300	90,000
Third Amendment | $100 million Term Loan
Debt Instrument [Line Items]
Expected term loan annual payment	6,200
$100 million Term Loan
Debt Instrument [Line Items]
Long-term debt, carrying Amount	92,500	100,000
Long-term debt, fair value	$ 92,500	$ 100,000