Equity-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended				12 Months Ended							1 Months Ended		12 Months Ended										12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Deferred Stock Units Selling, General and Administrative Expenses	Dec. 31, 2012 Deferred Stock Units Selling, General and Administrative Expenses	Dec. 31, 2011 Deferred Stock Units Selling, General and Administrative Expenses	Dec. 31, 2013 Non-Management Directors (Director Plan) Deferred Stock Units	Dec. 31, 2013 Stock Options	Dec. 31, 2012 Stock Options	Dec. 31, 2011 Stock Options	Dec. 31, 2013 Stock Options Minimum	Dec. 31, 2013 Stock Options Maximum	Dec. 31, 2013 SARs		Dec. 31, 2012 SARs		Dec. 31, 2011 SARs		Dec. 31, 2013 Restricted Stock	Dec. 31, 2012 Restricted Stock	Dec. 31, 2011 Restricted Stock	Dec. 31, 2010 Restricted Stock	Dec. 31, 2013 Restricted Stock Non-Management Directors (Director Plan)	Dec. 31, 2012 Restricted Stock Non-Management Directors (Director Plan)	Dec. 31, 2013 Restricted Stock ICG 2013 Performance Plan	Dec. 31, 2013 Restricted Stock ICG's Chief Executive Officer and ICG's President	Dec. 31, 2012 Restricted Stock ICG's Chief Executive Officer and ICG's President	Dec. 31, 2011 Restricted Stock ICG's Chief Executive Officer and ICG's President	Dec. 31, 2013 Restricted Stock First Vesting ICG's Employees	Dec. 31, 2013 Restricted Stock Second Vesting ICG's Employees	Dec. 31, 2013 Restricted Stock Third Vesting ICG's Employees	Dec. 31, 2013 Restricted Stock Minimum Condition One	Dec. 31, 2013 Restricted Stock Maximum Condition Two ICG 2013 Performance Plan	Dec. 31, 2013 Restricted Stock Award	Dec. 31, 2012 Restricted Stock Award	Dec. 31, 2011 Restricted Stock Award	Dec. 31, 2013 Restricted Stock Award Chief Executive Officer	Dec. 31, 2013 Performance Shares Employee	Dec. 31, 2013 Consolidated Entities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock awards vesting period									4 years			1 year	4 years	4 years																										4 years
Expiry period of incentive or non-qualified stock options granted from date of grant												8 years	10 years
SARs vesting on the first anniversary	25.00%
Remaining SARs vesting equally each month	75.00%
Subsequent vesting of remaining SARs, period	36 months
SARs exercisable														966,045		3,468,805		2,979,552
SARs weighted average base price														$ 8.50		$ 7.53		$ 7.42
SARs expected to vest														966,045
Equity-based compensation awards vesting on the first anniversary									25.00%																															25.00%
Remaining Equity-based compensation awards vesting equally each month									75.00%																															75.00%
Remaining awards vesting period									36 years																															36 months
Stock options,exercisable									250	1,729	183,082
Options, weighted average exercise price									$ 4.30	$ 6.94	$ 6.25
Weighted average remaining contractual life									5 years 3 months 18 days
Aggregate intrinsic value of the stock options, outstanding									$ 0.1
Stock Awards Vesting Shares																				1,185,071	1,217,463	1,225,785	60,500							57,248	49,967	130,440
Stock vesting description																														57,248 shares of restricted stock vest 25% each year over a four-year period	49,967 shares of restricted stock vest 12.5% on the nine-month anniversary of the grant date, and the remaining 87.5% every six months subsequent to the first vesting date	130,440 shares of restricted stock vest upon the achievement of certain performance goals
Number of Shares, Granted	30,540	32,923	13,571					29,250												183,190	116,973	1,181,910		30,750	18,750	130,440	916,666											2,575,000	158,942
Percentage of shares of restricted stock to vest upon achievement of performance condition																										50.00%
Weighted Average Fair Value, Exercised	$ 12.30	$ 9.42	$ 12.02											$ 8.64	[1]	$ 4.65	[1]	$ 5.82	[1]	$ 10.02	$ 10.01	$ 8.12				$ 13.09
Performance shares vesting conditions																										(1) is greater than or equal to 50%, all of that employee’s Performance Shares will vest or (2) is greater than 0% but less than 50%, a portion of that employee’s Performance Shares equal to two times the achievement percentage will vest.
Percentage of financial targets to be achieved for participants to receive award																																	50.00%	50.00%
Recorded equity compensation cost related to awards																											1.5
Equity compensation cost recognized																											0.4	0.9	0.2
Restricted stock awards vested																																			2.6	1.3	0.2
Shares surrendered for satisfying withholding taxes																																			46,616	39,817	3,351
Outstanding restricted shares expected to vest																																			818,405
Restricted stock awards, fair value																																						52.3	3.2
Expense associated with these DSUs					$ 0.4	$ 0.3	$ 0.2
Remaining awards vesting percentage on each anniversary																																								25.00%

[1] The exercise of SARs listed in this table resulted in the issuance of 992,390 shares, 9,818 shares and 20,229 shares of ICG’s Common Stock during the years ended December 31, 2013, 2012 and 2011.