Short-term and long-term debt - Additional Information (Detail)	3 Months Ended	12 Months Ended					12 Months Ended	3 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2013 GBP (£)	Feb. 15, 2013 USD ($)	Dec. 31, 2012 USD ($)	Jun. 22, 2012 USD ($)	Dec. 31, 2013 Subsequent Event GBP (£)	Sep. 30, 2013 Minimum	Sep. 30, 2013 Maximum	Feb. 15, 2013 Term Loan USD ($)	Jun. 22, 2012 Term Loan USD ($)	Dec. 31, 2013 Term Loan Base Rate	Dec. 31, 2013 Term Loan Eurodollar	Feb. 15, 2013 Revolving Credit Facility USD ($)	Jun. 22, 2012 Revolving Credit Facility USD ($)	Dec. 31, 2013 Revolving Credit Facility Base Rate	Dec. 31, 2013 Revolving Credit Facility Eurodollar	Dec. 31, 2013 Mortgage Note	Jun. 01, 2012 Mortgage Note USD ($)	Dec. 31, 2013 Vehicle And Equipment Loans Minimum	Dec. 31, 2013 Vehicle And Equipment Loans Maximum
Debt Disclosure [Line Items]
Maximum borrowing under PNC facility				$ 40,000,000		$ 27,000,000				$ 4,000,000	$ 4,000,000			$ 36,000,000	$ 23,000,000				$ 855,000
Fees and expenses relating to creation of PNC facility	150,000	150,000
Borrowings outstanding under PNC facility	19,080,000	19,080,000
Available borrowing under PNC facility	8,349,000	8,349,000
PNC Facility effective rate of interest	3.00%	3.00%	3.00%																4.00%	2.90%	8.90%
Interest rate description under PNC facility		Interest charges with respect to loans are computed on the actual principal amount of loans outstanding during the month at a rate per annum equal to (A) with respect to domestic rate loans, the sum of (i) a rate per annum equal to the higher of (1) the base commercial lending rate of PNC, (2) the federal funds open rate plus .5% and (3) the daily LIBOR plus 1%, plus (ii) .5% and (B) with respect to Eurodollar rate loans, the sum of the Eurodollar rate plus 2.75%.	Interest charges with respect to loans are computed on the actual principal amount of loans outstanding during the month at a rate per annum equal to (A) with respect to domestic rate loans, the sum of (i) a rate per annum equal to the higher of (1) the base commercial lending rate of PNC, (2) the federal funds open rate plus .5% and (3) the daily LIBOR plus 1%, plus (ii) .5% and (B) with respect to Eurodollar rate loans, the sum of the Eurodollar rate plus 2.75%.
PNC facility spread rate for calculation of interest												1.00%	2.75%			1.00%	2.75%
Production and importation permission from government agency, amount			63,000,000				51,000,000
Fixed charge coverage ratio								1.00	1.10
Debt instrument, description of variable rate basis												Base Rate plus one percent	Eurodollar Rate plus two and three quarters of one percent			Base Rate plus one percent	Eurodollar Rate plus two and three quarters of one percent
PNC credit Facility expiration date																		Jun. 01, 2017
Principal balance of this mortgage note	603,000	603,000			764,000
Capital leased assets gross	60,000	60,000
Earnings Before Interest Taxes Depreciation And Amortization	(2,010,000)	2,010,000
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest, Total		2,154,000
Interest Taxes Depreciation And Amortization		$ 144,000