Summary of Selected Information Related to Segments (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Segment Reporting Revenue Reconciling Item [Line Items]
Corporate other income (loss) (Note 10)	$ (45)		$ 1,470		$ (103)		$ 1,627
Noncontrolling interest (income) loss	458		(652)		4,044		(804)
Net income (loss) attributable to ICG Group, Inc.	(6,858)		(5,994)		12,210		(13,014)
Other
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss) attributable to ICG Group, Inc.	$ 413	[1]	$ 818	[1]	$ 3,941	[1]	$ 823	[1]

[1] The following table reflects the components in Other (in thousands):  Three Months Ended June 30,Six Months Ended June 30,  2013   2012   2013   2012  Corporate other income (loss) (Note 10)$(45)   $1,470    $(103)   $1,627   Noncontrolling interest (income) loss 458     (652)    4,044     (804)   $413    $818    $3,941    $823