Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended	12 Months Ended				24 Months Ended
	Jan. 31, 2009 interest_plan	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2008 interest_plan	Dec. 31, 2009 interest_plan	Oct. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Rent expense		$ 6.2	$ 3.0	$ 2.5
Lease renewal term		5 years
Number of carried interest plans | interest_plan	1				1	2
Carried interest rate (as a percent)						15.00%
Plan investment deployed amount approximately		$ 76.6
SAS
Loss Contingencies [Line Items]
Contingent consideration liability		$ 8.8					$ 8.4