Summary of Selected Information Related to Segments (Parenthetical) (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]
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
General and administrative
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									(19,132)		(23,113)		(17,086)
Impairment related and other
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									(2,953)		(865)		26
Corporate other income (loss)
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									(4,102)		57,824		43,207
Interest income
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									171		374		348
Income tax benefit (expense)
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									17,630		1		464
Equity loss
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)											(1)		(699)
Noncontrolling interest (income) loss
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									7,018		(592)		(2,235)
Other
Segment Reporting Revenue Reconciling Item [Line Items]
Net income (loss)									$ (1,368)	[1]	$ 33,628	[1]	$ 24,025	[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