Share-Based Compensation - Unrecognized Share-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 893
Average Expected Recognition Period	2 years 7 months 6 days
Stock Option Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	849
Average Expected Recognition Period	2 years 8 months 12 days
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense	$ 44
Average Expected Recognition Period	1 year