Earnings per share - Schedule of Computations of Basic and Diluted (Loss) Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Numerator:
Net (loss) income	$ (2,100)	$ 2,961	$ (5,027)	$ 4,111
Common Shares [Member]
Denominator:
Weighted average common shares outstanding-basic	9,243,773	9,064,537	9,171,942	9,064,537
Diluted effect of common stock equivalents
Weighted average common shares outstanding-diluted	9,243,773	9,064,537	9,171,942	9,064,537
(Loss) earnings per share of common stock - basic and diluted
(Loss) earnings per share of common stock - basic	$ (0.23)	$ 0.33	$ (0.55)	$ 0.45
(Loss) earnings per share of common stock - diluted	$ (0.23)	$ 0.33	$ (0.55)	$ 0.45