Stock Transactions and Unit Redemptions - Summary of Changes in Carrying Amount of Redeemable Partnership Interest (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Stock Transactions, Parenthetical Disclosures [Abstract]
Balance at beginning of period	$ 57,145	$ 59,501
Consolidated net income allocated to FPUs	5,588	3,227
Earnings distributions	(4,067)
Re-allocation of equity due to additional investment by founding/working partners		80
FPUs exchanged	(1,890)	(842)
FPUs redeemed	(334)	(243)
Other	(1)	3
Balance at end of period	$ 56,441	$ 61,726