Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Deferred Compensation Liability [Abstract]
Deferred compensation obligations	$ 6.0	$ 5.8
Trading securities	6.0	5.8
U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	155.1	157.7	$ 148.2
U.S. Pension Plans [Member] | Fair Value Excluding Investments Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	54.3	142.9
U.S. Pension Plans [Member] | Investments Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	100.8	14.8
Money Market Investments [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	3.9	11.4
Common Stocks [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		12.0
Corporate Bonds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	9.4	9.7
Pooled Equity Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	27.7	64.4
Pooled Fixed-income Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		27.3
US Government and Agency Securities [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	12.3	16.2
Other [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	1.0	1.9
Level 1 [Member] | U.S. Pension Plans [Member] | Fair Value Excluding Investments Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	27.8	101.3
Level 1 [Member] | Money Market Investments [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Level 1 [Member] | Common Stocks [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		9.4
Level 1 [Member] | Corporate Bonds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Level 1 [Member] | Pooled Equity Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	27.7	64.4
Level 1 [Member] | Pooled Fixed-income Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		27.3
Level 1 [Member] | US Government and Agency Securities [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Level 1 [Member] | Other [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	0.1	0.2
Level 2 [Member] | U.S. Pension Plans [Member] | Fair Value Excluding Investments Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	26.5	41.6
Level 2 [Member] | Money Market Investments [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	3.9	11.4
Level 2 [Member] | Common Stocks [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		2.6
Level 2 [Member] | Corporate Bonds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	9.4	9.7
Level 2 [Member] | Pooled Equity Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Level 2 [Member] | Pooled Fixed-income Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		0.0
Level 2 [Member] | US Government and Agency Securities [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	12.3	16.2
Level 2 [Member] | Other [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	0.9	1.7
Level 3 [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	$ 0.0	$ 0.0