Investments (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Investments
Fair value of investments	$ 19,476,000		$ 18,889,000
Total investment gains, net	587,000	172,000
Unrecognized carried interest	3,000,000		2,900,000
Payable to former employees	926,000		939,000
Management fees and other expense reimbursements	267,000		258,000
Investment in FATV
Investments
Fair value of investments	18,226,000		17,624,000
Total investment gains, net	601,000	138,000
Open commitments to fund portfolio	0
Total partnership capital	79,700,000		77,300,000
Share in management fee income	100,000	200,000
Employee Investment Funds, net of the Company's ownership interest
Investments
Fair value of investments	1,250,000		1,265,000
Total investment gains, net	(14,000)	34,000
Payable to former employees	900,000		900,000
Management fees and other expense reimbursements	300,000		300,000
Other investments
Investments
Fair value of investments	0		0
Warrants granted on redemption of investments in privately held companies
Investments
Fair value of investments	$ 0		$ 0
Aggregate exercise price of warrants (in dollars per share)	$ 1
Warrants granted on redemption of investments in privately held companies | Minimum
Investments
Ownership interest in investee due to warrant exercise on occurrence of liquidity event (as a percent)	0.40%
Warrants granted on redemption of investments in privately held companies | Maximum
Investments
Ownership interest in investee due to warrant exercise on occurrence of liquidity event (as a percent)	2.20%