Fair Value Measurements (Details) - USD ($) $ in Millions		Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Deferred Compensation Liability [Abstract]
Deferred compensation obligations		$ 5.8	$ 5.0
Trading securities		5.8	5.0
U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		157.7	148.2	$ 141.5
U.S. Pension Plans [Member] | Fair Value Excluding Investment Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		142.9	139.5
U.S. Pension Plans [Member] | Investment Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets	[1]	14.8	8.7
Money Market Investments [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		11.4	5.6
Common Stocks [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		12.0	19.8
Corporate Bonds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		9.7	9.3
Pooled Equity Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		64.4	56.8
Pooled Fixed-income Funds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		27.3	26.5
US Government and Agency Securities [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		16.2	18.7
Other [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		1.9	2.8
Level 1 [Member] | U.S. Pension Plans [Member] | Fair Value Excluding Investment Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		101.3	102.5
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	17.8
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		64.4	56.8
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	26.5
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		0.2	1.4
Level 2 [Member] | U.S. Pension Plans [Member] | Fair Value Excluding Investment Measured at Net Asset Value [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		41.6	37.0
Level 2 [Member] | Money Market Investments [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		11.4	5.6
Level 2 [Member] | Common Stocks [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		2.6	2.0
Level 2 [Member] | Corporate Bonds [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		9.7	9.3
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	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		16.2	18.7
Level 2 [Member] | Other [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		1.7	1.4
Level 3 [Member] | U.S. Pension Plans [Member]
U.S. pension plan assets [Abstract]
Fair value of plan assets		$ 0.0	$ 0.0

[1] As a practical expedient, the Company valued a collective trust fund using its net asset value per unit, and therefore, has not classified this investment within the fair value hierarchy.