Statements of Income and Expenses (Parenthetical) - shares		12 Months Ended
	May 01, 2015	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Class GP [Member]
Weighted average units outstanding	325.0000	402.17	[1]	325.64	[1]	325.00	[1]

[1] Class GP commenced on May 1, 2015 (325.0000 units)