Restricted Stock Units Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of Units
Outstanding at beginning of year	34,738	20,000	0
Granted	39,237	18,488	20,000
Released	(4,000)	0	0
Forfeited	(1,773)	(3,750)	0
Outstanding at end of year	68,202	34,738	20,000
Exercisable at end of year	0	0	0
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of year	2 years 6 months 29 days	1 year 7 months 17 days	2 years 1 month 13 days
Exercisable at end of year	0 years	0 years	0 years
Total aggregate intrinsic value of outstanding units	$ 6,362	$ 2,707	$ 1,618