Summary of significant accounting policies (Details 6) (USD $)	12 Months Ended					12 Months Ended	0 Months Ended			0 Months Ended		0 Months Ended		0 Months Ended		0 Months Ended				0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Mar. 31, 2011	Dec. 31, 2013 Restricted stock	Jul. 26, 2011 Restricted stock Restricted stock with performance goals Philip Beck	Dec. 31, 2013 Restricted stock Restricted stock with performance goals Philip Beck item	Jul. 26, 2011 Restricted stock Restricted stock with performance conditions	Jul. 26, 2011 Restricted stock Restricted stock with performance conditions Restricted stock with performance conditions, tranche 1	Dec. 31, 2013 Restricted stock Restricted stock with performance conditions Restricted stock with performance conditions, tranche 1 Minimum	Jul. 26, 2011 Restricted stock Restricted stock with performance conditions Restricted stock with performance conditions, tranche 2	Dec. 31, 2013 Restricted stock Restricted stock with performance conditions Restricted stock with performance conditions, tranche 2 Minimum	Jul. 26, 2011 Restricted stock Restricted stock with performance conditions Restricted stock with performance conditions, tranche 3	Dec. 31, 2013 Restricted stock Restricted stock with performance conditions Restricted stock with performance conditions, tranche 3 Minimum	Nov. 15, 2013 Restricted stock Restricted stock with market conditions	Jul. 26, 2011 Restricted stock Restricted stock with market conditions	Nov. 15, 2013 Restricted stock Restricted stock with market conditions Director, Chief Executive Officer and President 2012 Equity Incentive Plan item	Nov. 15, 2013 Restricted stock Restricted stock with market conditions Minimum Director, Chief Executive Officer and President 2012 Equity Incentive Plan	Jul. 26, 2011 Restricted stock Restricted stock with market conditions Restricted stock with market conditions, tranche 4	Dec. 31, 2013 Restricted stock Restricted stock with market conditions Restricted stock with market conditions, tranche 4 item	Dec. 31, 2013 Restricted stock Restricted stock with market conditions Restricted stock with market conditions, tranche 4 Minimum
Long-term incentive restricted stock agreements assumptions and vesting requirements
Stock granted (in shares)						875,583	915,000			305,000		47,000		469,000				200,000		94,000
Number of separate tranches in which stock-based award will vest								4
Adjusted EBITDA per fully diluted share when upon achievement shares will vest (in dollars per share)											$ 0.36		$ 0.64		$ 0.71
Fair value									$ 1,800,000	$ 700,000		$ 100,000		$ 1,000,000		$ 2,000	$ 5,600			$ 5,600
Fair market value of stock upon achievement of which share will be vested (in dollars per share)																						$ 12.00
Number of consecutive trading days during which the fair market value of the entity's common stock must exceed the specified price in order for the award to vest																					75
Valuation assumptions used for estimated fair value on grant date
Expected life																1 year 4 months 13 days	5 years 3 months 18 days
Expected volatility (percentage)																27.30%	31.68%
Risk-free interest rate (percentage)																0.23%	2.04%
Closing price of common stock as reported on NASDAQ (in dollars per share)	$ 2.78	$ 3.48	$ 2.27																$ 6.00
Number of consecutive trading days during which the closing price of the entity's common stock on the NASDAQ stock market must exceed the specified price in order for the award to vest																		30
Minimum per share consideration for change in control for shares to vest (in dollars per share)																			$ 6.00
Fair market value of stock immediately following change of control transaction, upon achievement of which share will be vested (in dollars per share)																			$ 6.00
Derecognition of notes payable
Notes payable derecognition amount on which statute of limitations expired				40,000	660,000
Derecognition of note payable			700,000
Other income recorded due to derecognition of note payable			700,000
Hurricane Sandy
Expense primarily related to the disposal of property and equipment	4,979	86,388
Insurance reimbursement		100,000
Insurance proceeds recorded as a gain in selling, general and administrative expenses	301,281
Capital additions related to Hurricane Sandy	$ 500,000