Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Income Taxes [Line Items]
U.S. corporate income tax rate					35.00%
Provisional tax benefit	$ 8.0	$ 206.7
Estimated undistributed foreign earnings and profits			$ 526.4
Provisional income tax expense	(6.9)		$ 71.0
Mandatory repatriation tax payable period			8 years
Valuation allowance, net operating losses	229.8		$ 229.8
Other Current Liabilities [Member]
Income Taxes [Line Items]
Repatriation tax liability	5.7		5.7
Other Long-term Liabilities [Member]
Income Taxes [Line Items]
Repatriation tax liability	65.3		65.3
Scenario, Plan [Member]
Income Taxes [Line Items]
U.S. corporate income tax rate				21.00%
Forecast [Member]
Income Taxes [Line Items]
U.S. corporate income tax rate				24.50%
Released [Member]
Income Taxes [Line Items]
Valuation allowance, deferred tax asset	335.0
Valuation allowance, net operating losses	2.7		2.7			$ 4.9
U.S. State Net Operating Losses [Member]
Income Taxes [Line Items]
Valuation allowance, net operating losses	$ 38.7		38.7
Federal Net Operating Losses [Member] | Forecast [Member]
Income Taxes [Line Items]
Valuation allowance, net operating losses				$ 40.0
Tax Year 2019 [Member]
Income Taxes [Line Items]
Limits on deducting compensation, including performance-base compensation			$ 1.0