Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Stock-based compensation expense	$ 1,151,199	$ 1,190,697	$ 1,102,617
Tax benefit recognized	285,068	219,626	244,746
Windfall or shortfall tax impacts	452,000	274,000	21,000
Federal | Minimum
Income Taxes [Line Items]
Tax years subject to examination	2009
Federal | Maximum
Income Taxes [Line Items]
Tax years subject to examination	2012
State | Minimum
Income Taxes [Line Items]
Tax years subject to examination	2009
State | Maximum
Income Taxes [Line Items]
Tax years subject to examination	2012
Italy
Income Taxes [Line Items]
Net operating losses	9,144,154
Italy | Minimum
Income Taxes [Line Items]
Tax years subject to examination	2009
Italy | Maximum
Income Taxes [Line Items]
Tax years subject to examination	2012
Massachusetts
Income Taxes [Line Items]
Investment tax credit carry-forward	$ 298,769
Massachusetts | Maximum
Income Taxes [Line Items]
Investment tax credit carry-forward, expiration period	2021