Common Unit Repurchase Plans and Retirement - Company's Repurchase Activities (Parenthetical) (Detail) - USD ($) shares in Millions, $ in Millions		3 Months Ended
	Nov. 16, 2020	Dec. 31, 2019	Nov. 30, 2020	Aug. 31, 2020	Jul. 31, 2020	May 31, 2020	Apr. 30, 2020	Feb. 29, 2020	Jan. 31, 2020
Capital Unit [Line Items]
Company's common units authorized for repurchase				6.0	2.0	3.6	0.1	1.1	0.1
Private Transaction
Capital Unit [Line Items]
Company's common units repurchased		0.6
Common Stock Available for Repurchase Under Open Market Transactions
Capital Unit [Line Items]
Company's common units authorized for repurchase				4.9
Common Stock Available for Repurchase Under Open Market Transactions | Subsequent Event
Capital Unit [Line Items]
Company's common units authorized for repurchase			4.2
Common Stock Available for Repurchase Under Privately Negotiated Transactions
Capital Unit [Line Items]
Company's common units authorized for repurchase				1.1
Common Stock Available for Repurchase Under Privately Negotiated Transactions | Subsequent Event
Capital Unit [Line Items]
Company's common units authorized for repurchase			1.1
Unit Purchase Agreement | Subsequent Event | Moab Partners, L.P.
Capital Unit [Line Items]
Company's common units repurchased	1.4
Aggregate consideration paid for common units purchased	$ 13.8