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

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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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Stock-Based Compensation - Other Equity Award (Details) - Restricted Stock Awards - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense			$ 2.5	$ 1.4
RSA 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awarded					$ 0.5
Share-based compensation expense		$ 1.0
RSA 2012 \| Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock upon vesting	$ 2.0