Income Taxes - Reconciliation between statutory rate and effective rate (Details)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Unrecognized tax benefits activity
Federal tax at statutory rate	21.00%	21.00%
Stock compensation and other permanent differences	(31.00%)	2.00%
Tax credits		1.00%
Valuation allowance	10.00%	(23.00%)
Total		1.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(2))
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
-URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817

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-Section 50
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Effective income tax rate reconciliation stock compensation and other permanent differences percent.

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