Debt Facilities - Senior Credit Facility - Additional Information (Details) - Silicon Valley Bank - USD ($)	12 Months Ended
	Dec. 31, 2016	May 31, 2016
Term Borrowings
Line Of Credit Facility [Line Items]
Amount of outstanding borrowings	$ 10,500,000	$ 10,500,000
Line of credit facility, interest rate description	interest on term borrowings accrues at a floating rate equal to the lender’s prime rate plus 2.25% during a one year interest-only period and at a floating rate equal to the lender’s prime rate plus 1.75% after expiration of the interest-only period (6.0% at December 31, 2016).
Refinance in outstanding borrowings		8,200,000
Line of credit facility, month and year of first required payment	2017-06
Line of credit facility, frequency of payments	36 equal monthly installments
Term Borrowings | Term Loan Prepaid On or Prior To First Anniversary of May 2016 Amendment
Line Of Credit Facility [Line Items]
Prepayment fee	$ 210,000
Term Borrowings | Term Loan Prepaid After First Anniversary but On or Prior To Second Anniversary of May 2016 Amendment
Line Of Credit Facility [Line Items]
Prepayment fee	$ 105,000
Term Borrowings | Prime Rate
Line Of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate	6.00%
Term Borrowings | Prime Rate | One Year Interest Only Period
Line Of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate	2.25%
Term Borrowings | Prime Rate | After Expiration of Interest Only Period
Line Of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate	1.75%
Standby Letters of Credit
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 5,000,000
Equipment Term Loan Facility
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 2,000,000	$ 2,000,000
Senior Credit Facility
Line Of Credit Facility [Line Items]
Term borrowings, extended maturity date	2017-12
Term loan, revolver and equipment loan borrowings outstanding, excluding unamortized debt issuance costs	$ 12,400,000
Unamortized debt issuance costs	$ 149,000
Credit facility, weighted average interest rate	5.90%
Senior Credit Facility | Term Borrowings
Line Of Credit Facility [Line Items]
Line of credit facility, maturity date	2020-05
Senior Credit Facility | Revolver Borrowings
Line Of Credit Facility [Line Items]
Amount of outstanding borrowings	$ 0
Line of credit facility, maximum borrowing capacity	$ 15,000,000
Line of credit facility, interest rate description	Interest on revolver borrowings is payable monthly and accrues at a floating rate equal to the lender’s prime rate plus 2.25% at all times when our cash held at the bank plus the amount available to borrow on the revolver is less than or equal to $8.5 million, and 1.75% when our cash held at the bank plus the amount available to borrow on the revolver is greater than $8.5 million for a period of at least 60 consecutive days (5.5% at December 31, 2016). The maturity date of the revolver is December 2017.
Line of credit facility, basis spread on variable rate	5.50%
Line of credit facility, amount available to borrow	$ 8,500,000
Senior Credit Facility | Revolver Borrowings | Cash Held At Bank Plus Amount Available To Borrow on Revolver Is Less Than or Equal To $8.5 Million
Line Of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate	2.25%
Senior Credit Facility | Revolver Borrowings | Cash Held At Bank plus Amount Available To Borrow on Revolver Is Greater Than $8.5 Million
Line Of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate	1.75%
Senior Credit Facility | Equipment Term Loan Facility
Line Of Credit Facility [Line Items]
Amount of outstanding borrowings	$ 1,900,000
Line of credit facility, interest rate description	Accrue interest at a floating rate equal to the lender’s prime rate plus 1.75%
Line of credit facility, frequency of payments	36 equal monthly installments
Line of credit facility, maturity date	2020-05
Line of credit facility, interest rate	5.50%
Senior Credit Facility | Equipment Term Loan Facility | Equipment Loan Prepaid On or Prior To First Anniversary of Date Such Equipment Loan Was Borrowed
Line Of Credit Facility [Line Items]
Percentage of prepayment fee	2.00%
Senior Credit Facility | Equipment Term Loan Facility | Equipment Loan Prepaid After First Anniversary of Date Such Equipment Loan Was Borrowed
Line Of Credit Facility [Line Items]
Percentage of prepayment fee	1.00%
Senior Credit Facility | Equipment Term Loan Facility | Prime Rate
Line Of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate	1.75%