Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Aggregate number of common shares reserved for future issuance.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under share-based payment arrangement.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Stockholders' Equity (Schedule of Shares of Common Stock Reserved for Issuance) (Details) - USD ($)			3 Months Ended	12 Months Ended
	Mar. 09, 2018	Sep. 13, 2016	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock				331,193	331,193
Total common stock reserved for future issuance				33,763,713
Total fair value of options vested				$ 2,000,000	$ 4,800,000
Weighted-average fair value of options granted during the period				$ 0.79	$ 0.47
Weighted-average period			1 year 7 months 6 days	1 year 4 months 24 days
Unrecognized compensation expense			$ 700,000	$ 1,000,000
2019 LPC Purchase Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total common stock reserved for future issuance				14,500,000
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding				15,881,406
Available for future grants	7,500,000	3,000,000		3,050,799
Vesting period expiration			10 years	10 years
Number of shares authorized to be issued under the plan	16,050,000
2012 Equity Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total common stock reserved for future issuance		125,000				1,100,000
Vesting period			4 years	4 years
2012 Equity Incentive Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years	3 years
2001 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding				315
2001 Stock Option Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to be issued under the plan				426,030