CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Temporary Equity
Common stock subject to repurchase	3,565,692	4,427,084
Stockholders Equity
Common stock par value	$ 0.01	$ 0.01
Common stock shares authorized	90,000,000	90,000,000
Common stock shares issued	39,903,469	34,994,828
Common stock shares outstanding	37,783,578	34,030,351
Treasury Stock held, at cost	2,119,891	2,072,810