Earnings Per Limited Partner Unit - Net Income Allocation and Per Unit Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Basic and Diluted Earnings Per Limited Partner:
Net income		$ 27,755	$ 2,315
Less General Partner’s interest in net income		192	15
Net income available to limited partners		27,563	2,300
Less dilutive impact of theoretical distribution of earnings under FASB ASC 260-10-45-60		4,351
Limited Partner’s interest in net income under FASB ASC 260-10-45-60		$ 23,212	$ 2,300
Per unit data:
Basic and diluted net income available to limited partners		$ 0.58	$ 0.04
Less dilutive impact of theoretical distribution of earnings under FASB ASC 260-10-45-60		0.09
Limited Partner’s interest in net income under FASB ASC 260-10-45-60	[1]	$ 0.49	$ 0.04
Weighted average number of Limited Partner units outstanding		47,266	52,905

[1] See Note 16 - Earnings Per Limited Partner Unit.