Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements Of Operations [Abstract]
Revenue	$ 140,527	$ 115,710	$ 90,252
Operating expenses
Cost of revenue	85,572	71,050	56,920
Selling, general and administrative	45,099	42,206	34,578
Research and development	12,436	10,644	9,015
Amortization of intangible assets	1,412	1,357	205
Impairment related and other	970	1,182	5,192
Total operating expenses	145,489	126,439	105,910
Operating income (loss)	(4,962)	(10,729)	(15,658)
Other income (loss), net	42,624	74,147	16,578
Interest income	393	330	446
Interest expense	(577)	(366)	(216)
Income (loss) from continuing operations before income taxes and equity loss	37,478	63,382	1,150
Income tax benefit (expense)	4,287	(254)	39,510
Equity loss	(11,964)	(16,022)	(12,131)
Income (loss) from continuing operations	29,801	47,106	28,529
Income (loss) from discontinued operations, including gain on sale		802
Net income (loss)	29,801	47,908	28,529
Less: Net income attributable to the noncontrolling interest	2,235	1,319	12,995
Net income (loss) attributable to ICG Group, Inc.	27,566	46,589	15,534
Amounts attributable to ICG Group, Inc.:
Net income (loss) from continuing operations	27,566	45,977	15,534
Net income (loss) from discontinued operations		612
Net income (loss)	$ 27,566	$ 46,589	$ 15,534
Basic income (loss) per share attributable to ICG Group, Inc.:
Income (loss) from continuing operations	$ 0.75	$ 1.26	$ 0.42
Income (loss) on discontinued operations		$ 0.02
Net income (loss)	$ 0.75	$ 1.28	$ 0.42
Shares used in computation of basic income (loss) per share	36,656	36,427	36,660
Diluted income (loss) per share attributable to ICG Group, Inc.:
Income (loss) from continuing operations	$ 0.74	$ 1.24	$ 0.42
Income (loss) on discontinued operations		$ 0.02
Net income (loss)	$ 0.74	$ 1.26	$ 0.42
Shares used in computation of diluted income (loss) per share	37,460	37,064	36,705