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

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

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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Share-based Compensation - Options Information and Valuation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized amount, options	$ 0.3		$ 0.3
Number of stock options exercisable	191,116		191,116
Weighted average exercise price of stock options that are exercisable	$ 12.84		$ 12.84
Remaining contractual life of exercisable stock options			7 years 1 month 6 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Expiration period			10 years
Share-based compensation recognized cost	$ 0.1	$ 0.1	$ 0.3	$ 0.2
Unrecognized cost, period for recognition			1 year 1 month 6 days