Fair Value Disclosures - Additional Information (Detail) (USD $)	3 Months Ended
	Dec. 31, 2013
Fair Value Assets Liabilities Quantitative Information [Line Items]
Percentage of financial assets derived from Level 1 inputs measured at fair value	91.00%
Change in unrealized gain (loss)	$ 0
Significant Other Inputs (Level 2)
Fair Value Assets Liabilities Quantitative Information [Line Items]
Percentage of financial assets derived from Level 2 inputs measured at fair value	7.00%
Significant Unobservable Inputs (Level 3)
Fair Value Assets Liabilities Quantitative Information [Line Items]
Percentage of financial assets derived from Level 3 inputs measured at fair value	2.00%
Offshore fund | Significant Other Inputs (Level 2) | Energy and natural resources sectors
Fair Value Assets Liabilities Quantitative Information [Line Items]
Trading securities, at fair value	877,108
Venture capital investments | Medical and medical technology sectors
Fair Value Assets Liabilities Quantitative Information [Line Items]
Fair value investment entities calculating net asset value per share unfunded commitments	$ 62,500
Available-for-sale securities | Offshore fund | Significant Other Inputs (Level 2)
Fair Value Assets Liabilities Quantitative Information [Line Items]
Redemption description of investment	First business day of each month after providing a redemption notice at least forty-five days prior to the proposed redemption date.
Trading securities | Offshore fund | Significant Other Inputs (Level 2)
Fair Value Assets Liabilities Quantitative Information [Line Items]
Redemption description of investment	First business day of each month after providing a redemption notice at least forty-five days prior to the proposed redemption date.