Stock-Based Compensation (Narrative) (Details) $ / shares in Units, $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($) item $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans \| item	4
Unrecognized compensation cost related to unvested awards under share-based plans \| $	$ 9.3
Cost expected to be recognized over a weighted average period	1 year 6 months
Share-based Payment Arrangement, Expense \| $	$ 6.5	$ 5.1
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	313,697	1,531,702
Granted (in dollars per share) \| $ / shares	$ 18.81	$ 6.87
Restricted Stock Units (RSUs) [Member] \| Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years	3 years
Granted (in shares)	261,073	1,387,602
Restricted Stock Units (RSUs) [Member] \| Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year	1 year
Granted (in shares)	52,624	144,100
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	100,000	300,000
Vesting period	4 years	4 years
Stock option exercised (in shares)	657,500	74,000
Options Granted (in dollars per share) \| $ / shares	$ 8.51	$ 3.02
Options exercised and vested in period, total intrinsic value \| $	$ 25.3	$ 6.5
Restricted Stock Units And Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value \| $	$ 7.6	$ 5.3

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Share Based Compensation Arrangement By Share Based Payment Award Options Exercises And Vested In Period Total Intrinsic Value

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

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

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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

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