Changes in Stock Appreciation Rights (Detail) (SARs, USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
SARs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
SARs, Granted
SARs, Exercised	24,352	[1]	28,864	[1]	318,277	[1]	155,488	[1]
SARs, Forfeited			5,346				5,346
Weighted Average Base Price, Granted
Weighted Average Base Price, Exercised	$ 9.56	[1]	$ 7.40	[1]	$ 8.19	[1]	$ 8.78	[1]
Weighted Average Base Price, Forfeited			$ 9.95				$ 9.95
Weighted Average Fair Value, Granted
Weighted Average Fair Value, Exercised	$ 4.92	[1]	$ 4.44	[1]	$ 4.72	[1]	$ 5.27	[1]
Weighted Average Fair Value, Forfeited			$ 5.39				$ 5.39

[1] The exercise of SARs listed in the three-month period table resulted in the issuance of 8,634 shares and 6,999 shares of ICG’s Common Stock during the three months ended June 30, 2014 and 2013, respectively. The exercise of SARs listed in the six-month period table resulted in the issuance of 129,093 shares and 44,232 shares of ICG’s Common Stock during the six months ended June 30, 2014 and 2013, respectively.