Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Oct. 02, 2012	Dec. 31, 2013 Segment	Dec. 31, 2012	Dec. 31, 2011
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment		1
Estimated useful lives of intangibles	5 years
Aggregate assets under management		$ 600,000,000	$ 700,000,000	$ 1,000,000,000
Investment management fees		1,700,000	2,500,000	3,300,000
Management fees net of fees paid		$ 96,100,000	$ 53,700,000	$ 36,400,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred sales charges receiving period		1 year
Deferred commissions amortization period		1 year
Estimated useful lives of intangibles		1 year
Minimum [Member] | Furniture and Office Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives of fixed assets		3 years
Minimum [Member] | Computer Equipment and Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives of fixed assets		3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred sales charges receiving period		5 years
Deferred commissions amortization period		5 years
Estimated useful lives of intangibles		16 years
Maximum [Member] | Furniture and Office Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives of fixed assets		10 years
Maximum [Member] | Computer Equipment and Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives of fixed assets		5 years