Consolidated Statements of Financial Condition (Unaudited) (Parenthetical)	Mar. 31, 2018 $ / shares shares	Dec. 31, 2017 $ / shares shares
Class 0 Units [Member]
Members' capital:
Capital units, issued (in units)	160,253.743	164,393.539
Capital units, outstanding (in units)	160,253.743	164,393.539
Capital units, value (in dollars per unit) | $ / shares	143.24	140.90
Class 2 Units [Member]
Members' capital:
Capital units, issued (in units)	133,519.048	137,512.329
Capital units, outstanding (in units)	133,519.048	137,512.329
Capital units, value (in dollars per unit) | $ / shares	103.44	101.94