Income Taxes - Income Tax Benefit Attributable to Our Loss from Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. federal income tax benefit at statutory rates	$ (5,591)	$ (3,891)
State income tax benefit, net of federal benefit	(502)	(350)
Research and experimentation credits	(268)	(181)
Deferred tax asset adjustment	65	76
Other	137	188
Change in valuation allowance	6,159	4,158
Total	$ 0	$ 0