Condensed Statements of Financial Condition (Parenthetical) - shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
General Partner: units issued (in units)	100,000	100,000
General Partner: units outstanding (in units)	100,000	100,000
Limited partners: units issued (in units)	94,894,404	96,558,278
Limited partners: units outstanding (in units)	94,894,404	96,558,278