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Total amount of additional stock-based compensation cost recognized from occurrence of event accelerating recognition of cost and the excess of fair value of modified award over the fair value of the award immediately before modification.

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Share Based Compensation Arrangement By Share Based Payment Award Options Vested Grant Date Fair Value

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- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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- Definition

Aggregate number of common shares reserved for future issuance.

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- Definition

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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Amount of cost to be recognized for option under share-based payment arrangement.

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Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance.

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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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- Definition

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

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

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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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Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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

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Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended		6 Months Ended	9 Months Ended
	Feb. 03, 2021	Jan. 21, 2020	Aug. 31, 2020	May 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance					17,218,269			17,218,269		16,386,314
Total stock-based compensation					$ 3,280	$ 2,074		$ 9,439	$ 6,609
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Executives and employees stock options granted			1,107,250
Total stock-based compensation					700	$ 200		2,200	$ 200
Total unrecognized stock-based compensation related to unvested stock options					6,100			6,100
Service Vesting Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation related to unvested stock options					$ 26,700			$ 26,700
Weighted-average period								2 years 10 months 24 days
2018 Equity Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance					1,037,500			1,037,500			37,500
Common shares authorized to be issued during the period	500,000						500,000
Stock option life in years								10 years
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance					5,123,736			5,123,736
Common shares authorized to be issued during the period		4,312,500
Stock option life in years								10 years
Percentage threshold of outstanding shares increased annually under the plan								4.00%
Stock option grants description								the number of shares equal to 4% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31.
2008 Plan, 2015 Plan and 2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares authorized to be issued during the period								945,139
Weighted-average grant date fair values of options granted					$ 13.95	$ 8.85		$ 12.27	$ 8.77
Issuance of common stock for exercise of stock options, Shares						0		51,827	0
Aggregate intrinsic value of options exercised					$ 200			$ 300
Total grant date fair value of options vested					$ 3,300	$ 700		$ 9,200	$ 4,500
2008 Plan, 2015 Plan and 2018 Plan [Member] \| Share Based Compensation Arrangement Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant expiration period after specified event				75 days
Compensation costs relating to vesting acceleration and modification						$ 2,200			$ 2,200