Restricted stock (Details) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Jan. 31, 2012
Shares Available for Grant, Balances as of December 31, 2012		763,295
Shares Available for Grant, Authorized	0	0		338,295
Shares Available for Grant, Granted		(248,500)
Shares Available for Grant, Forfeited	6,000	8,500
Shares Available for Grant, Balances as of June 30, 2013	523,295	523,295	763,295
Number of Shares Outstanding, Balances as of December 31, 2012		267,000
Number of Shares, Authorized		0
Number of Shares, Granted		248,500
Number of Shares, Forfeited	(6,000)	(8,500)
Number of Shares, Vested		(100,000)
Number of Shares Outstanding, Balances as of June 30, 2013	407,000	407,000	267,000
Weighted Average Grant Date Fair Value, Balances as of December 31, 2012 (in dollars per share)		$ 3.56
Weighted Average Grant Date Fair Value, Authorized (in dollars per share)		$ 0
Weighted Average Grant Date Fair Value, Granted (in dollars per share)		$ 1.76
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share)		$ 2.94
Weighted Average Grant Date Fair Value, Vested (in dollars per share)		$ 3.14
Weighted Average Grant Date Fair Value, Balances as of June 30, 2013 (in dollars per share)	$ 3.67	$ 3.67	$ 3.56
Average Remaining Term, Balance (in years)		2 years	1 year 10 months 6 days