Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accumulated depreciation (in dollars)	$ 113,828	$ 113,184
Fair value of other assets (in dollars)	$ 37,770	$ 36,480
Treasury stock shares	453,066	453,066
Class A
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock shares authorized	1,000,000,000	1,000,000,000
Common stock shares issued	41,427,886	40,436,580
Common stock shares outstanding	40,974,820	39,983,514
Class B
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock shares authorized	175,000,000	175,000,000
Common stock shares issued	0	0
Common stock shares outstanding	0	0
Class C
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock shares authorized	90,000,000	90,000,000
Common stock shares issued	18,773,891	19,810,707
Common stock shares outstanding	18,773,891	19,810,707
Class D
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock shares authorized	175,000,000	175,000,000
Common stock shares issued	79,610,490	79,610,490
Common stock shares outstanding	79,610,490	79,610,490