Stock-Based Compensation - Black-Scholes Option Pricing Model Assumptions (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-Based Compensation
Weighted-average grant date fair value of options granted	$ 8.23	$ 2.26	$ 0.85
Fair value of stock options vested	$ 2.6	$ 1.8	$ 1.8
Unrecognized compensation cost	$ 4.2
Weighted-average period of unrecognized compensation cost to be recognized	1 year 3 months 18 days
Minimum
Stock-Based Compensation
Risk-free interest rate	0.90%	0.30%	1.60%
Expected term (years)	5 years	5 years	3 years
Volatility	60.00%	59.00%	46.00%
Maximum
Stock-Based Compensation
Risk-free interest rate	1.30%	0.60%	1.90%
Expected term (years)	6 years	6 years	6 years
Volatility	61.00%	60.00%	51.00%

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

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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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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

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

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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- Definition

Expected term of 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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

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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