Quarterly report pursuant to Section 13 or 15(d)

Financing Arrangements - Additional Information (Details)

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Financing Arrangements - Additional Information (Details)
1 Months Ended 3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
$ / shares
shares
Mar. 31, 2017
Installment
$ / shares
shares
Jun. 30, 2017
USD ($)
$ / shares
shares
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
$ / shares
shares
Jun. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Debt Instrument [Line Items]              
Notes payable $ 13,500,000   $ 13,500,000   $ 13,500,000   $ 12,000,000
Weighted average interest rate     11.42% 11.00% 11.50% 11.00%  
Interest expense on debt     $ 400,000 $ 200,000 $ 700,000 $ 500,000  
Amortization of debt issuance costs     $ 50,000 $ 32,000 84,000 $ 64,000  
Net proceeds from Initial public offering excluding underwriting discounts and commissions $ 32,400,000       $ 32,426,000    
The March 2017 Preferred stock warrant              
Debt Instrument [Line Items]              
Number of shares called by warrant | shares 61,363 76,704 61,363   61,363    
Class of warrant, exercise price | $ / shares [1] $ 5.8667   $ 5.8667   $ 5.8667    
The March 2017 Preferred stock warrant | Series B-1 Convertible Preferred Stock              
Debt Instrument [Line Items]              
Number of shares called by warrant | shares 61,363 76,704 61,363   61,363    
Class of warrant, exercise price | $ / shares   $ 5.8667          
Minimum              
Debt Instrument [Line Items]              
Net proceeds from Initial public offering excluding underwriting discounts and commissions $ 25,000,000            
Maximum              
Debt Instrument [Line Items]              
Number of shares called by warrant | shares 84,000   84,000   84,000    
Notes Payable | 2015 Term Note              
Debt Instrument [Line Items]              
Notes payable $ 13,100,000   $ 13,100,000   $ 13,100,000   $ 11,700,000
Debt instrument maturity date   Oct. 31, 2020          
Debt instrument number of periodic payment of principal and interest | Installment   36          
Notes Payable | 2015 Term Note | Minimum              
Debt Instrument [Line Items]              
Debt instrument variable rate   11.00%          
Notes Payable | 2015 Term Note | Minimum | Three -Month LIBOR              
Debt Instrument [Line Items]              
Debt instrument basis spread   2.50%          
Notes Payable | 2015 Term Note | Maximum | Three -Month LIBOR              
Debt Instrument [Line Items]              
Debt instrument basis spread   7.50%          
[1] This warrant was issued in connection with the amended 2015 Term Note. The number of shares underlying the warrant issued in March 2017 was originally 76,704 and, pursuant to its terms, was reduced to 61,363 shares upon the closing of the Company’s IPO. See Note 7, Financing Arrangements, for further details regarding this warrant.