Stock-Based Compensation - Long-Term Incentive Plans Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation not yet recognized	$ 8.0	$ 8.1
LTIPs | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation not yet recognized	4.1	1.6
LTIPs | Cash Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation not yet recognized	$ 2.4	$ 0.1