Additional Information Related to Equity-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	$ 1,880	$ 1,621	$ 6,039	$ 4,676
Unrecognized Equity-Based Compensation	10,844		10,844
Weighted Average Years Remaining of Equity-Based Compensation
SARs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	599	661	1,801	1,887
Unrecognized Equity-Based Compensation	2,192		2,192
Weighted Average Years Remaining of Equity-Based Compensation	1 year 10 months 24 days		1 year 10 months 24 days
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	1,020	737	3,446	2,134
Unrecognized Equity-Based Compensation	6,794		6,794
Weighted Average Years Remaining of Equity-Based Compensation	2 years 3 months 18 days		2 years 3 months 18 days
DSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	96	87	282	332
Unrecognized Equity-Based Compensation	160		160
Weighted Average Years Remaining of Equity-Based Compensation	4 months 24 days		4 months 24 days
Equity-Based Compensation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	1,715	1,485	5,529	4,353
Unrecognized Equity-Based Compensation	9,146		9,146
Weighted Average Years Remaining of Equity-Based Compensation
Non- Controlling Interest
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation	165	136	510	323
Unrecognized Equity-Based Compensation	$ 1,698		$ 1,698
Weighted Average Years Remaining of Equity-Based Compensation	2 years 9 months 18 days		2 years 9 months 18 days