Total Unrecognized Compensation Costs Related to Unvested Stock-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	$ 8,454
Weighted-average remaining recognition period (in years)	2.5
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	5,898
Weighted-average remaining recognition period (in years)	2.7
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	$ 2,556
Weighted-average remaining recognition period (in years)	2.2