Share-based Compensation - Principal Assumptions Utilized in Valuing Service Condition SSARs (Details) - Stock Settled Stock Appreciation Rights (SSARS) [Member] - Black Scholes Merton Option Pricing Model - $ / shares	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.31%
Expected life (in years)	4 years
Expected volatility	42.99%
Weighted average grant date fair value (in dollars per share)	$ 22.57	$ 10.01
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate		1.38%
Expected life (in years)		4 years 6 months
Expected volatility		31.70%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate		1.74%
Expected life (in years)		5 years
Expected volatility		32.42%