Change in Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at the beginning of the year	$ 50.4	$ 40.3
Service costs	2.2	1.4
Interest costs	1.0	1.0
Settlements	0.0	0.5
Actuarial losses	0.7	7.9
Benefits paid	(0.8)	(0.4)
Foreign currency exchange rate changes	7.5	(0.3)
Projected benefit obligation at the end of the year	61.0	50.4
Accumulated benefit obligation at the end of the year	55.5	45.6
Defined benefit pension plan, liabilities	61.0	50.4
Defined benefit pension plan liabilities, current	0.9	0.7
Defined benefit pension plan, liabilities, noncurrent	$ 60.1	$ 49.7