Stockholders' Equity - Unrecognized Compensation Expense and July 2021 CEO Stock Grant (Details) $ in Millions		9 Months Ended
Jul. 15, 2021 USD ($) D shares	Sep. 30, 2021 USD ($) Milestone shares
Unrecognized stock-based compensation expense
Total unrecognized stock-based compensation expense, options \| $		$ 3.8
Weighted-average period over which unrecognized stock-based compensation expense is expected to be recognized	5 years
Award service period	5 years
Stock Options
Unrecognized stock-based compensation expense
Total unrecognized stock-based compensation expense, options \| $		$ 3.8
Weighted-average period over which unrecognized stock-based compensation expense is expected to be recognized		2 years 14 days
Restricted Stock Units
Unrecognized stock-based compensation expense
Total unrecognized stock-based compensation expense, restricted stock units \| $	$ 8.9	$ 11.8
Weighted-average period over which unrecognized stock-based compensation expense is expected to be recognized		4 years 1 month 2 days
Granted (in shares)		160,729
Restricted stock units vested (in shares)		5,987
Restricted Stock Units \| Share-based Payment Arrangement, Tranche One
Unrecognized stock-based compensation expense
Restricted stock units vested (in shares)	25,000
Restricted Stock Units \| Share-based Payment Arrangement, Tranche Two
Unrecognized stock-based compensation expense
Restricted stock units vested (in shares)	25,000
Restricted Stock Units \| Share-based Payment Arrangement, Tranche Three
Unrecognized stock-based compensation expense
Restricted stock units vested (in shares)	25,000
Restricted Stock Units \| CEO
Unrecognized stock-based compensation expense
Granted (in shares)	125,000
Performance Stock Units
Unrecognized stock-based compensation expense
Total unrecognized stock-based compensation expense, restricted stock units \| $	$ 7.2	$ 7.5
Weighted-average period over which unrecognized stock-based compensation expense is expected to be recognized		4 years 8 months 12 days
Granted (in shares)		233,658
Number of days, achievement of milestone stock price \| D	30
Stock price milestones \| Milestone		0
Percentage of predetermined performance achievement	100.00%
Award service period		3 years
Performance Stock Units \| CEO
Unrecognized stock-based compensation expense
Granted (in shares)	225,000

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Share-based Compensation Arrangement by Share-based Payment Award, Award Service Period

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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 grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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