Investments - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended			3 Months Ended			1 Months Ended		6 Months Ended	12 Months Ended		12 Months Ended			12 Months Ended			1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jul. 31, 2012 GCP	Dec. 31, 2013 GCP	Dec. 31, 2012 GCP	Dec. 31, 2012 GCPE	Dec. 31, 2013 GCP I	Dec. 31, 2012 GCP I	Dec. 31, 2012 GCP II	Jun. 30, 2012 GCP II	Dec. 31, 2012 GCP II	Dec. 31, 2011 GCP II	Dec. 31, 2013 GCP II	Dec. 31, 2011 GSAVP	Dec. 31, 2013 Barrow Street III	Dec. 31, 2012 Barrow Street III	Dec. 31, 2013 Iridium common stock	Dec. 31, 2012 Iridium common stock	Dec. 31, 2011 Iridium common stock	Oct. 31, 2011 Minimum Iridium common stock
Fair Value, Measurement Inputs, Disclosure [Line Items]
Sale of capital interests				$ 2,000,000			$ 27,200,000						$ 44,800,000		$ 4,600,000
Investments Repurchase Agreement Amount To Be Paid										14,300,000	1,300,000	15,600,000
Investments in merchant banking funds	11,745,000	16,772,000			0	1,367,000		2,257,000	2,247,000							1,798,000	1,985,000
Book value of investment sold (percent)							90.00%
Merchant banking loss							(3,400,000)
Amortization period of gains	5 years
Deferred gain on sale of certain merchant banking assets	195,000	260,000	811,000
Investment related to noncontrolling interests								100,000	300,000	1,100,000		1,100,000		900,000
Other Commitment																$ 300,000
Duration of plan to sell common shares																					2 years
Sale of common stock (shares)																		5,084,016	3,850,000	870,000
Average price per share (usd per share)																		$ 6.73	$ 7.91	$ 6.72
Investment owned (shares)																			5,084,016
Share price (usd per share)																			$ 6.72
The percentage of ownership interest which is fully diluted (percent)																			7.00%