Subsequent Event (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Aug. 03, 2018	Jul. 11, 2018	Jun. 30, 2018	Jun. 30, 2017
Subsequent Event [Line Items]
Sale proceeds of common shares			$ 28,957
Warrants outstanding to purchase common stock				0
Silicon Valley Bank [Member]
Subsequent Event [Line Items]
Warrants exercise price per common share			$ 2.43
Warrant exercisable term			10 years
Common Shares [Member]
Subsequent Event [Line Items]
Stock Issued			3,440,000
Subsequent Event [Member] | Term Loan [Member]
Subsequent Event [Line Items]
Repayment of outstanding borrowings of loan agreement	$ 12,000
Repayment of final payment fee	$ 485
Subsequent Event [Member] | Term Loan [Member] | Loan Agreement [Member] | Silicon Valley Bank [Member]
Subsequent Event [Line Items]
Debt instrument, payment commencing period	2018-09
Debt instrument, interest only payment end date	Mar. 31, 2020
Debt instrument principal repayment period	30 months
Debt instrument, maturity date	Sep. 01, 2022
Debt instrument, final payment fee percentage	6.50%
Debt instrument prepayment fee	$ 295
Debt instrument default interest payment above normal interest rate	5.00%
Warrants outstanding to purchase common stock	40,000
Warrants exercise price per common share	$ 9.79
Warrant exercisable term	10 years
Subsequent Event [Member] | Term Loan [Member] | Loan Agreement [Member] | Silicon Valley Bank [Member] | Prior to First Anniversary [Member]
Subsequent Event [Line Items]
Debt instrument, prepayment fee payable on outstanding principal, in percentage	3.00%
Subsequent Event [Member] | Term Loan [Member] | Loan Agreement [Member] | Silicon Valley Bank [Member] | After First Anniversary, but Prior to Second Anniversary [Member]
Subsequent Event [Line Items]
Debt instrument, prepayment fee payable on outstanding principal, in percentage	2.00%
Subsequent Event [Member] | Term Loan [Member] | Loan Agreement [Member] | Silicon Valley Bank [Member] | After Second Anniversary [Member]
Subsequent Event [Line Items]
Debt instrument, prepayment fee payable on outstanding principal, in percentage	1.00%
Subsequent Event [Member] | Term Loan [Member] | Loan Agreement [Member] | Silicon Valley Bank [Member] | Prime Rate [Member]
Subsequent Event [Line Items]
Debt instrument, floating interest rate	0.50%
Subsequent Event [Member] | Jefferies and Stifel [Member] | At-The-Market Equity Offering Sales Agreement [Member]
Subsequent Event [Line Items]
Sale proceeds of common shares	$ 14,820
Subsequent Event [Member] | Jefferies and Stifel [Member] | At-The-Market Equity Offering Sales Agreement [Member] | Maximum [Member]
Subsequent Event [Line Items]
Sale proceeds of common shares		$ 50,000
Subsequent Event [Member] | Common Shares [Member] | Jefferies and Stifel [Member] | At-The-Market Equity Offering Sales Agreement [Member]
Subsequent Event [Line Items]
Stock Issued	1,600,000