Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Cash and securities segregated, at cost	$ 946,093	$ 565,264
Capital:
Limited partners units issued (in units)	268,893,534	272,301,827
Limited partners, units outstanding (in units)	268,893,534	272,301,827