Summary of Selected Information Related to Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	$ 17,680		$ 16,071	$ 13,476	$ 11,974	$ 9,031		$ 7,998	$ 5,400	$ 4,211	$ 59,201		$ 26,640		$ 12,885
Net income (loss)	200,181		(3,332)	(6,858)	19,068	14,662		21,341	(5,994)	(7,020)	209,059		22,989		27,566
Assets	529,604					447,059					529,604		447,059		306,820
Capital expenditures, net											(1,243)		(6,990)		(912)
Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue											59,201		26,640		12,885
Net income (loss)											(20,346)		(21,079)		(7,490)
Assets	195,566					188,120					195,566		188,120		39,501
Capital expenditures, net											(1,209)		(5,487)		(826)
Vertical Cloud | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue											58,772		26,026		12,885
Net income (loss)											(18,026)		(18,244)		(7,490)
Assets	179,687					173,300					179,687		173,300		30,023
Capital expenditures, net											(1,183)		(5,487)		(826)
Vertical Cloud Venture | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue											429		614
Net income (loss)											(2,320)		(2,835)
Assets	15,879					14,820					15,879		14,820		9,478
Capital expenditures, net											(26)
Dispositions
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)											230,773		10,440		11,031
Assets						242,938							242,938		138,481
Other
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)											(1,368)	[1]	33,628	[1]	24,025	[1]
Assets	334,038	[1]				16,001	[1]				334,038	[1]	16,001	[1]	128,838	[1]
Capital expenditures, net											$ (34)	[1]	$ (1,503)	[1]	$ (85)	[1]

[1] The following table reflects the components of Net income (loss) attributable to ICG Group, Inc. included in Other (in thousands):     Year Ended December 31,     2013   2012   2011  General and administrative  $(19,132)  $(23,113)  $(17,086)   Impairment related and other(2,953)(865)26 Corporate other income (loss) (Note 13)(4,102)57,824  43,207 Interest income171  374  348 Income tax benefit (expense)17,6301  464 Equity loss—(1)  (699) Noncontrolling interest (income) loss7,018  (592)(2,235)  Net income (loss)  $(1,368)  $33,628  $24,025