Income Taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In accordance with applicable accounting guidance, the income tax provision for the three and nine months ended September 30, 2017 is based on the estimated annual effective tax rate for fiscal year 2017. The estimated effective tax rate may be subject to adjustment in subsequent quarterly periods as the estimates of pretax income for the year, along with other items that may affect the rate, change. The Company's provision for income taxes reflected an effective tax rate of approximately 0.1% and 1.0% for the three months ended September 30, 2017 and 2016, respectively, and 1.8% and 1.2% for the nine months ended September 30, 2017 and 2016, respectively. For the three and nine months ended September 30, 2017 and 2016, the Company's effective tax rate was lower than the U.S. federal statutory rate primarily due to changes to its valuation allowance. The Company has significant deferred tax assets related to its net operating loss carryforwards and tax credits and has provided a valuation allowance for the full amount of its deferred tax assets, as it is not more likely than not that any future benefit from deductible temporary differences, net operating loss carryforwards, and tax credit carryforwards will be realized. This assessment requires judgment as to the likelihood and amounts of future taxable income by tax jurisdiction. To date, the Company has provided a full valuation allowance against its deferred tax assets as it believes the objective and verifiable evidence of its historical pretax net losses outweighs any positive evidence of its forecasted future results. Although the Company believes that its tax estimates are reasonable, the ultimate tax determination involves significant judgment that is subject to audit by tax authorities in the ordinary course of business. The Company will continue to monitor the positive and negative evidence, and it will adjust the valuation allowance as sufficient objective positive evidence becomes available. The Company increased both its net operating loss deferred tax asset and its valuation allowance by $17.3 million upon adoption of ASU No. 2016-09 relating to certain tax deductions associated with stock option transactions greater than the stock-related compensation expense for financial statement purposes. The Company had no unrecognized tax benefits as of September 30, 2017. The Company's tax years 2013 through 2016 remain open to examination by the major taxing jurisdictions to which the Company is subject. However, the Company is not currently under examination by any taxing jurisdiction.

Income Taxes

In accordance with applicable accounting guidance, the income tax provision for the three and nine months ended September 30, 2017 is based on the estimated annual effective tax rate for fiscal year 2017. The estimated effective tax rate may be subject to adjustment in subsequent quarterly periods as the estimates of pretax income for the year, along with other items that may affect the rate, change.

The Company's provision for income taxes reflected an effective tax rate of approximately 0.1% and 1.0% for the three months ended September 30, 2017 and 2016, respectively, and 1.8% and 1.2% for the nine months ended September 30, 2017 and 2016, respectively. For the three and nine months ended September 30, 2017 and 2016, the Company's effective tax rate was lower than the U.S. federal statutory rate primarily due to changes to its valuation allowance.

The Company has significant deferred tax assets related to its net operating loss carryforwards and tax credits and has provided a valuation allowance for the full amount of its deferred tax assets, as it is not more likely than not that any future benefit from deductible temporary differences, net operating loss carryforwards, and tax credit carryforwards will be realized. This assessment requires judgment as to the likelihood and amounts of future taxable income by tax jurisdiction.

To date, the Company has provided a full valuation allowance against its deferred tax assets as it believes the objective and verifiable evidence of its historical pretax net losses outweighs any positive evidence of its forecasted future results. Although the Company believes that its tax estimates are reasonable, the ultimate tax determination involves significant judgment that is subject to audit by tax authorities in the ordinary course of business. The Company will continue to monitor the positive and negative evidence, and it will adjust the valuation allowance as sufficient objective positive evidence becomes available.

The Company increased both its net operating loss deferred tax asset and its valuation allowance by $17.3 million upon adoption of ASU No. 2016-09 relating to certain tax deductions associated with stock option transactions greater than the stock-related compensation expense for financial statement purposes.

The Company had no unrecognized tax benefits as of September 30, 2017. The Company's tax years 2013 through 2016 remain open to examination by the major taxing jurisdictions to which the Company is subject. However, the Company is not currently under examination by any taxing jurisdiction.