Income Taxes	9 Months Ended
Sep. 30, 2013
Income Taxes
Income Taxes	11. Income Taxes The Company did not record a provision or benefit for income taxes during the nine months ended September 30, 2013 and 2012, respectively. The Company continues to maintain a valuation allowance for its U.S. federal and state deferred tax assets. On January 2, 2013, The American Taxpayer Relief Act of 2012, or ATRA, was signed into law. Under prior law, a taxpayer was entitled to a research tax credit for qualifying amounts incurred through December 31, 2011. The ATRA extends the research credit for two years for qualified research expenditures incurred through the end of 2013. The extension of the research credit is retroactive and includes amounts incurred after 2011. At September 30, 2013, the Company had $0.7 million of unrecognized tax benefit, none of which, if recognized, would affect the effective tax rate as most of the unrecognized tax benefit is deferred tax assets currently offset by a valuation allowance. The Company has not recognized any interest and penalties related to uncertain tax positions as part of the income tax provision. The Company files annual income tax returns in the United States only. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves, as well as the related interest, in light of changing facts and circumstances. Settlement of any particular position could require the use of cash. As of September 30, 2013, changes to the Company’s uncertain tax positions in the next twelve months that are reasonably possible are not expected to have a significant impact on the Company’s financial position or results of operations.

Income Taxes

9 Months Ended

Sep. 30, 2013

11. Income Taxes

The Company did not record a provision or benefit for income taxes during the nine months ended September 30, 2013 and 2012, respectively. The Company continues to maintain a valuation allowance for its U.S. federal and state deferred tax assets.

On January 2, 2013, The American Taxpayer Relief Act of 2012, or ATRA, was signed into law. Under prior law, a taxpayer was entitled to a research tax credit for qualifying amounts incurred through December 31, 2011. The ATRA extends the research credit for two years for qualified research expenditures incurred through the end of 2013. The extension of the research credit is retroactive and includes amounts incurred after 2011.

At September 30, 2013, the Company had $0.7 million of unrecognized tax benefit, none of which, if recognized, would affect the effective tax rate as most of the unrecognized tax benefit is deferred tax assets currently offset by a valuation allowance.

The Company has not recognized any interest and penalties related to uncertain tax positions as part of the income tax provision.

The Company files annual income tax returns in the United States only. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves, as well as the related interest, in light of changing facts and circumstances. Settlement of any particular position could require the use of cash. As of September 30, 2013, changes to the Company’s uncertain tax positions in the next twelve months that are reasonably possible are not expected to have a significant impact on the Company’s financial position or results of operations.