Fair Value Measurements - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Fair Value, Option, Quantitative Disclosures [Line Items]
Transfers between Level 1 , 2 and 3 in fair value measurement hierarchy	$ 0	$ 0	$ 0	$ 0
Unfunded Commitments	19,137		19,137		27,135
EGCP III [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Unfunded Commitments	12,688		12,688
End of the investment period			Oct. 12, 2016
Remaining commitments date			Oct. 12, 2023
COF2 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Unfunded Commitments	4,805		4,805
End of the investment period			Nov. 11, 2016
Remaining commitments date			Nov. 11, 2019
CP II [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Unfunded Commitments	$ 1,644		$ 1,644
End of the investment period			Feb. 25, 2017