Additional Information Related to Equity-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	$ 6,739	$ 2,096	$ 10,615	$ 4,159
Unrecognized Equity-Based Compensation	52,255		52,255
DSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	99	96	245	186
Unrecognized Equity-Based Compensation	215		215
Weighted Average Years Remaining of Equity-Based Compensation			6 months
SARs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	201	601	451	1,202
Unrecognized Equity-Based Compensation	887		887
Weighted Average Years Remaining of Equity-Based Compensation			1 year 7 months 13 days
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	6,268	1,237	9,561	2,426
Unrecognized Equity-Based Compensation	49,926		49,926
Weighted Average Years Remaining of Equity-Based Compensation			1 year 9 months 18 days
Equity-Based Compensation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	6,568	1,934	10,257	3,814
Unrecognized Equity-Based Compensation	51,028		51,028
Non-Controlling Interest
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	171	162	358	345
Unrecognized Equity-Based Compensation	$ 1,227		$ 1,227
Weighted Average Years Remaining of Equity-Based Compensation			1 year 9 months 22 days