Share Based Compensation - Outstanding and exercisable options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Outstanding and exercisable options, number of shares
Outstanding at end of year	9,733,091
Exercisable at end of year	6,802,328
Outstanding and exercisable options, weighted average exercise price
Outstanding at beginning of year	$ 5.09
Outstanding at end of year	4.54	$ 5.09
Exercisable at end of year	$ 5.14
Weighted average remaining contractual life (in years)	6 years 8 months 15 days	6 years 6 months 18 days
Weighted average remaining contractual life for vested options (in years)	5 years 11 months 1 day	5 years 11 months 4 days
Unrecognized compensation cost	$ 5.1	$ 11.4
Expected period for recognition	1 year 5 months 23 days	2 years 3 months 7 days
Plans 2011 and 2019 and 2021 Inducement
Outstanding and exercisable options, number of shares
Outstanding at beginning of year	8,726,130
Outstanding at end of year	9,733,091	8,726,130
Exercisable at end of year	6,802,328	5,144,488
Outstanding and exercisable options, weighted average exercise price
Exercisable at end of year		$ 5.32
2011 Plan
Outstanding and exercisable options, number of shares
Outstanding at beginning of year	1,694,233	1,802,672
Expired	(11,272)	(1,336)
Exercised	(50,476)	(107,103)
Outstanding at end of year	1,632,485	1,694,233
Exercisable at end of year	1,632,485	1,694,233
Outstanding and exercisable options, weighted average exercise price
Outstanding at beginning of year	$ 2.09	$ 2.05
Exercised	1.04	1.52
Expired	4.01	0.91
Outstanding at end of year	2.11	2.09
Exercisable at end of year	$ 2.11	$ 2.09
2019 Plan
Outstanding and exercisable options, number of shares
Outstanding at beginning of year	6,406,897	5,314,312
Granted	1,652,000	1,875,400
Expired	(68,238)	(58,617)
Exercised		(7,000)
Forfeited	(386,053)	(156,198)
Cancelled	(561,000)	(561,000)
Outstanding at end of year	7,604,606	6,406,897
Exercisable at end of year	4,850,552	3,228,422
Outstanding and exercisable options, weighted average exercise price
Outstanding at beginning of year	$ 5.82	$ 8.35
Granted	1.62	3.61
Exercised		3.74
Forfeited	4.42	6.13
Cancelled		21.73
Expired	7.42	11.52
Outstanding at end of year	4.97	5.82
Exercisable at end of year	$ 6.09	$ 6.93
2021 Inducement Plan
Outstanding and exercisable options, number of shares
Outstanding at beginning of year	625,000	503,000
Granted		122,000
Expired	(30,750)
Forfeited	(98,250)
Outstanding at end of year	496,000	625,000
Exercisable at end of year	319,291	221,833
Outstanding and exercisable options, weighted average exercise price
Outstanding at beginning of year	$ 5.74	$ 6.41
Exercised		2.98
Forfeited	3.31
Expired	6.22
Outstanding at end of year	5.99	5.74
Exercisable at end of year	$ 6.24	$ 6.42

The number of shares under options that were cancelled during the reporting period pertaining to the stock option plan.

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Weighted average grant-date fair value of options cancelled.

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- Definition

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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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of share options (or share units) exercised during the current period.

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