Additional Information Related to Equity-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation	$ 6,634	$ 4,260	$ 3,067
Unrecognized Equity-Based Compensation at Dec. 31, 2012	15,392
Equity-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation	5,778	3,787	2,345
Unrecognized Equity-Based Compensation at Dec. 31, 2012	12,216
Noncontrolling Interest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation	856	473	722
Unrecognized Equity-Based Compensation at Dec. 31, 2012	3,176
Weighted Average Years Remaining of Equity-Based Compensation at Dec. 31, 2012	3 years 1 month 6 days
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation	2,488	2,252	2,037
Unrecognized Equity-Based Compensation at Dec. 31, 2012	4,009
Weighted Average Years Remaining of Equity-Based Compensation at Dec. 31, 2012	2 years 2 months 27 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation			1
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation	2,871	832	103
Unrecognized Equity-Based Compensation at Dec. 31, 2012	8,149
Weighted Average Years Remaining of Equity-Based Compensation at Dec. 31, 2012	3 years
DSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation	419	703	204
Unrecognized Equity-Based Compensation at Dec. 31, 2012	$ 58
Weighted Average Years Remaining of Equity-Based Compensation at Dec. 31, 2012	2 months 12 days