Share-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share Based Compensation [Abstract]
Stock-based compensation expense under share based plans	$ 346,000	$ 359,000	$ 838,000	$ 706,000
Cash received from employee stock purchase plan	273,000	115,000	416,000	240,000
Unrecognized compensation expense related to unvested portion of all share-based compensation	$ 2,200,000		$ 2,200,000
Expected weighted average recognition period for unrecognized compensation expense			1 year 4 months 24 days