Income (loss) per share Schedule of the computation of basic and diluted net income (loss) per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Annual dividend rate			8.00%
Net income (loss)	$ 1,737	$ (900)	$ 2,082	$ (2,242)
Less: undistributed earnings allocated to participating securities	(9)	0	(1,299)	0
Net income (loss) attribuatble to common stockholders	1,728	(900)	783	(2,242)
Adjustment to diluted net income for participating securities	1	0	26	0
Weighted-average shares used to compute basic net income (loss) per common share	22,450	3,589	15,973	3,284
Diluted net income (loss) attributable to common shareholders	$ 1,729	$ (900)	$ 809	$ (2,242)
Weighted average shares used to compute dluted income (loss) per common share	25,337	3,589	18,751	3,284
Net income (loss) Per Share, Basic	$ 0.08	$ (0.25)	$ 0.05	$ (0.68)
Net income (loss) per common share - diluted	$ 0.07	$ (0.25)	$ 0.04	$ (0.68)
Stock options and restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Incremental Common Shares Attributable to Share-based Payment Arrangements	2,818	0	2,688	0
Stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Incremental Common Shares Attributable to Warrants	69	0	90	0