Debt	3 Months Ended
Mar. 31, 2018
Debt Disclosure [Abstract]
Debt	5. DEBT The Company did not have any outstanding debt as of March 31, 2018 and December 31, 2017. Line of credit The Company first entered into a loan and security agreement (the “LSA”) with Silicon Valley Bank (“Bank’) in July 2011. The LSA was amended and restated in subsequent periods. The amended and restated loan and security agreement (the “Restated 2014 LSA”) entered into in November 2014, provides advances under a revolving line of credit up to $30.0 million and provides for letters of credit to be issued up to the lesser of the available line of credit, reduced by outstanding advances and drawn but unreimbursed letters of credit, or $5.0 million. The financial and non-financial covenants as well as the term of the agreement were updated in subsequent amendments to the Restated 2014 LSA. In June 2017, the Company entered into a second amendment to the Restated 2014 LSA. The advances under the second amendment carry a floating per annum interest rate equal to, at the Company’s option, (1) the prime rate or (2) LIBOR plus 2.75%, or the prime rate plus 1% depending on certain ratios. The amendment further changed the financial covenant to maintain a current ratio (calculated as current assets, divided by current liabilities less deferred revenue) greater than or equal to 1.25. The revolving line of credit terminates on June 30, 2019 at which time all outstanding advances becomes due and payable. As of March 31, 2018 and December 31, 2017, the Company was in compliance with all of the covenants in the amended Restated 2014 LSA. The Company did not have any borrowings outstanding on the revolving line of credit as of March 31, 2018 and December 31, 2017. The Company had $2.2 million and $1.5 million outstanding in letters of credit as of March 31, 2018 and December 31, 2017, respectively. The interest rate on the line of credit was 4.63% and 4.31% as of March 31, 2018 and December 31, 2017, respectively. Term loan In June 2017, the Company entered into a subordinated loan agreement (“2017 Agreement”) with the Bank. The 2017 Agreement provided for a term loan borrowing of $40.0 million, with a minimum of $25.0 million to be initially drawn at the close of the agreement with the remaining amount available for a 24 month period, to be drawn in no less than $5.0 million increments. Advances under the term loan incur a facility fee equal to 1% of the drawn borrowings, in addition to interest payments at an interest rate equal to, at the Company’s option, (1) the prime rate plus 3.5% or (2) LIBOR plus 6.5%, subject to a 1% LIBOR floor. Additionally, the borrowings incur payment in kind interest fees equal to 2.5%, accruing to the unpaid borrowings balance, compounded monthly. Payment in kind interest may be settled in cash, at the Company’s election, during the term or at maturity. The Company is also obligated to pay final payment fees ranging from 1% to 4% depending on the timing of the payment. On October 31, 2017 the Company repaid the entire amount outstanding, and subsequently terminated the 2017 Agreement. In connection with the 2017 Agreement the Company issued 0.4 million warrants to purchase shares of Series H convertible preferred stock, with an exercise price of $9.17340. The warrants are exercisable up to ten years from the date of issuance. Upon the repayment of the amounts borrowed and the subsequent termination of the 2017 Agreement, the Company cancelled 0.1 million warrants that were contingent on future borrowings. The Bank exercised 0.1 million warrants during the year ended December 31, 2017 and 0.2 million warrants during the three months ended March 31, 2018. There were no outstanding warrants as of March 31, 2018.

5. DEBT

The Company did not have any outstanding debt as of March 31, 2018 and December 31, 2017.

Line of credit

The Company first entered into a loan and security agreement (the “LSA”) with Silicon Valley Bank (“Bank’) in July 2011. The LSA was amended and restated in subsequent periods. The amended and restated loan and security agreement (the “Restated 2014 LSA”) entered into in November 2014, provides advances under a revolving line of credit up to $30.0 million and provides for letters of credit to be issued up to the lesser of the available line of credit, reduced by outstanding advances and drawn but unreimbursed letters of credit, or $5.0 million. The financial and non-financial covenants as well as the term of the agreement were updated in subsequent amendments to the Restated 2014 LSA.

In June 2017, the Company entered into a second amendment to the Restated 2014 LSA. The advances under the second amendment carry a floating per annum interest rate equal to, at the Company’s option, (1) the prime rate or (2) LIBOR plus 2.75%, or the prime rate plus 1% depending on certain ratios. The amendment further changed the financial covenant to maintain a current ratio (calculated as current assets, divided by current liabilities less deferred revenue) greater than or equal to 1.25. The revolving line of credit terminates on June 30, 2019 at which time all outstanding advances becomes due and payable. As of March 31, 2018 and December 31, 2017, the Company was in compliance with all of the covenants in the amended Restated 2014 LSA.

The Company did not have any borrowings outstanding on the revolving line of credit as of March 31, 2018 and December 31, 2017. The Company had $2.2 million and $1.5 million outstanding in letters of credit as of March 31, 2018 and December 31, 2017, respectively. The interest rate on the line of credit was 4.63% and 4.31% as of March 31, 2018 and December 31, 2017, respectively.

Term loan

In June 2017, the Company entered into a subordinated loan agreement (“2017 Agreement”) with the Bank. The 2017 Agreement provided for a term loan borrowing of $40.0 million, with a minimum of $25.0 million to be initially drawn at the close of the agreement with the remaining amount available for a 24 month period, to be drawn in no less than $5.0 million increments. Advances under the term loan incur a facility fee equal to 1% of the drawn borrowings, in addition to interest payments at an interest rate equal to, at the Company’s option, (1) the prime rate plus 3.5% or (2) LIBOR plus 6.5%, subject to a 1% LIBOR floor. Additionally, the borrowings incur payment in kind interest fees equal to 2.5%, accruing to the unpaid borrowings balance, compounded monthly. Payment in kind interest may be settled in cash, at the Company’s election, during the term or at maturity. The Company is also obligated to pay final payment fees ranging from 1% to 4% depending on the timing of the payment. On October 31, 2017 the Company repaid the entire amount outstanding, and subsequently terminated the 2017 Agreement.

In connection with the 2017 Agreement the Company issued 0.4 million warrants to purchase shares of Series H convertible preferred stock, with an exercise price of $9.17340. The warrants are exercisable up to ten years from the date of issuance. Upon the repayment of the amounts borrowed and the subsequent termination of the 2017 Agreement, the Company cancelled 0.1 million warrants that were contingent on future borrowings. The Bank exercised 0.1 million warrants during the year ended December 31, 2017 and 0.2 million warrants during the three months ended March 31, 2018. There were no outstanding warrants as of March 31, 2018.