Company's Repurchase Activities (Parenthetical) (Detail) - shares shares in Thousands	Nov. 30, 2018	Aug. 31, 2018	Jul. 31, 2018	Feb. 28, 2018	Jan. 31, 2018
Capital Unit [Line Items]
Company's common units authorized for repurchase		5,550	3,000	5,500	2,200
Repurchase Plan
Capital Unit [Line Items]
Company's common units authorized for repurchase		5,550	2,900	5,500	2,200
Open Market Transactions | Subsequent Event
Capital Unit [Line Items]
Company's common units authorized for repurchase	2,500
Privately Negotiated Transactions | Subsequent Event
Capital Unit [Line Items]
Company's common units authorized for repurchase	2,500