Redeemable Convertible Preferred Stock Preferred Stock Warrants (Details) (USD $) In Thousands, except Share data, unless otherwise specified		3 Months Ended		6 Months Ended		12 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2012	Jun. 30, 2012 Series D Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2011 Series D Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2012 Series D Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2011 Series D Redeemable Convertible Preferred Stock [Member]	Dec. 31, 2011 Series D Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2012 Series C Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2011 Series C Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2012 Series C Redeemable Convertible Preferred Stock [Member]	Jun. 30, 2011 Series C Redeemable Convertible Preferred Stock [Member]	Dec. 31, 2011 Series C Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of shares entited by rights issued	352,178	62,000		62,000			41,904		41,904
Exercise price of rights (usd per share)	26	20.73		20.73			2.983		2.983
Warrant liability		$ 489		$ 489		$ 426	$ 830		$ 830		$ 724
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		$ (84)	$ (183)	$ (63)	$ (66)		$ (106)	$ (55)	$ (106)	$ (143)
Risk free interest rate				0.40%		0.40%			0.30%		0.30%
Expected volatility				41.20%		42.90%			42.00%		41.00%
Expected life (in years)				3 years		3 years			2 years		2 years
Dividend yield				0.00%		0.00%			0.00%		0.00%