Related Party Transactions (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	May 24, 2021
Chairman of the Board of Directors
Related Party Transaction [Line Items]
Related party expenses incurred	$ 0.0		$ 0.8
Director
Related Party Transaction [Line Items]
Related party expenses incurred		$ 0.1
Former Director
Related Party Transaction [Line Items]
Related party expenses incurred		1.6	$ 2.4
Class A Voting Common Shares | Subsequent Event | Chairman of the Board of Directors
Related Party Transaction [Line Items]
Percentage of common stock outstanding held by MHR Fund Management				23.00%
Class B Non-Voting Common Shares | Subsequent Event | Chairman of the Board of Directors
Related Party Transaction [Line Items]
Percentage of common stock outstanding held by MHR Fund Management				11.00%
Maximum | Chairman of the Board of Directors
Related Party Transaction [Line Items]
Related party expenses incurred		$ 0.1
Maximum | Director
Related Party Transaction [Line Items]
Related party expenses incurred	$ 0.1