Net Income per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator (basic and diluted):
Net income	$ 3,224	$ 3,871	$ 5,234	$ 6,900
Accretion of redemption premium expense	(778)	(2,924)	(2,301)	(5,692)
Net income (loss) attributable to common stockholders for basic EPS	2,446	947	2,933	1,208
Add back: accretion of redemption premium related to dilutive redeemable preferred stock	(86)		(260)
Net income (loss) attributable to common stockholders for diluted EPS	$ 2,360	$ 947	$ 2,673	$ 1,208
Denominator (basic):
Weighted average common shares outstanding	14,268	1,535	7,907	1,534
Denominator (diluted):
Weighted average common shares outstanding	14,268	1,535	7,907	1,534
Dilutive stock options and awards outstanding	1,305	1,195	1,109	1,122
Weighted average common shares from stock warrants	2,793	2,854	2,626	2,854
Weighted average common shares from convertible preferred stock	5,983	10,866	9,041	10,866
Net weighted average common shares outstanding	24,349	16,450	20,683	16,376
Net income (loss) per share attributable to holders of common stock:
Basic	$ 0.17	$ 0.62	$ 0.37	$ 0.79
Diluted	$ 0.10	$ 0.06	$ 0.13	$ 0.07