Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017
Income Taxes [Abstract]
Effective income tax rate	(144.90%)		(3.20%)	(41.30%)		6.10%
Tax Credit Carryforward [Line Items]
Tax benefit from foreign development tax credit	$ (13.6)
Foreign Tax Reforms [Member]
Net of valuation allowance, classification [Abstract]
Valuation allowance - deferred tax assets	35.1			$ 35.1
Changes in deferred tax asset valuation allowances	1.0	$ (2.0)
Domestic Tax Jurisdiction [Member]
Net of valuation allowance, classification [Abstract]
Valuation allowance - deferred tax assets	6.9			$ 6.9
Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Tax benefit from foreign development tax credit			$ (2.2)			$ (5.7)
U.S Tax Reforms [Member]
Effective income tax rate reconciliation [Abstract]
Provisional discrete tax charges	(10.8)				$ 38.0
Deferred tax assets - change in amount	(9.4)				(19.0)
Transition tax charge	(3.1)				$ 19.0
Domestic Tax Jurisdiction [Member]
Effective income tax rate reconciliation [Abstract]
Provisional discrete tax charges	1.7
Transition tax charge	$ 15.9