Consolidated Statements of Financial Condition (Parenthetical)	Dec. 31, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares
Class 0 Units [Member]
Members' capital:
Capital units, issued (in units)	164,393.539	319,296.990
Capital units, outstanding (in units)	164,393.539	319,296.990
Capital units, value (in dollars per unit) | $ / shares	140.90	146.92
Class 2 Units [Member]
Members' capital:
Capital units, issued (in units)	137,512.329	154,401.114
Capital units, outstanding (in units)	137,512.329	154,401.114
Capital units, value (in dollars per unit) | $ / shares	101.94	107.43