Pro Forma Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Dilutive Securities Included In Computation Of Earnings Per Share [Line Items]
Revenue	$ 183,995	$ 165,551
Net income (loss) attributable to ICG Group, Inc.	$ 21,511	$ 27,860
Net income (loss) per diluted share attributable to ICG Group, Inc.	$ 0.59	$ 0.74

The portion of profit or loss, net of income taxes, which is attributable to the parent that would have been reported if the pro forma conditions specified had occurred in the relevant periods.

No definition available.

Name:	icge_ProFormaNetIncomeLoss
Namespace Prefix:	icge_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration