Restricted Stock Units Activity (Detail) (Restricted stock units, USD $)	12 Months Ended
	Dec. 31, 2011 Year	Dec. 31, 2010 Year
Restricted stock units
Number of Units
Outstanding at beginning of year	20,000	0
Granted	18,488	20,000
Forfeited	(3,750)	0
Outstanding at end of year	34,738	20,000
Exercisable at end of year	0	0
Vested and expected to vest in the future	28,493	20,000
Weighted average remaining contractual life (in years)
Outstanding at end of year	1.63	2.12
Exercisable at end of year	0.00	0.00
Vested and expected to vest in the future	1.60	2.12
Aggregate intrinsic value
Outstanding at end of year	$ 2,706,784	$ 1,618,400
Exercisable at end of year	0	0
Vested and expected to vest in the future	$ 2,220,173	$ 1,618,400