Additional Information Related to Equity-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	$ 6,357	$ 1,880	$ 16,972	$ 6,039
Unrecognized Equity-Based Compensation	43,775		43,775
DSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	99	96	347	282
Unrecognized Equity-Based Compensation	116		116
Weighted Average Years Remaining of Equity-Based Compensation			3 months 18 days
SARs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	195	599	646	1,801
Unrecognized Equity-Based Compensation	666		666
Weighted Average Years Remaining of Equity-Based Compensation			1 year 6 months 4 days
Restricted Stock Member
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	5,870	1,020	15,431	3,446
Unrecognized Equity-Based Compensation	42,015		42,015
Weighted Average Years Remaining of Equity-Based Compensation			2 years 6 months
Equity-Based Compensation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	6,164	1,715	16,424	5,529
Unrecognized Equity-Based Compensation	42,797		42,797
Non-controlling Interest
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	193	165	548	510
Unrecognized Equity-Based Compensation	$ 978		$ 978
Weighted Average Years Remaining of Equity-Based Compensation			1 year 6 months 26 days