Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets (liabilities)
Operating losses carried forward	$ 11,382	$ 7,626
Tax credits	1,243	702
Stock compensation	1,414	1,726
Other	530	170
Valuation allowance	$ (14,569)	$ (10,224)

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

+ References

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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