Stock-Based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Time-based restricted stock unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation Expense	$ 0.6	$ 0.1
Associated tax benefit from stock-based compensation expense	0.1	0.1
Unrecognized compensation expense	$ 4.9
Period for unrecognized compensation expense expected to be recognized	2 years 7 months 28 days
Time-based stock option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation Expense	$ 0.3	0.1
Associated tax benefit from stock-based compensation expense	0.1	$ 0.1
Unrecognized compensation expense	$ 2.0
Period for unrecognized compensation expense expected to be recognized	2 years 7 months 6 days

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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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 tax benefit for recognition of expense of award under share-based payment arrangement.

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