Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
One-time benefit on preliminary re-measurement of net deferred tax liability	$ 9.0
Income Tax Authority [Line Items]
Federal statutory income tax rate				35.00%
Federal [Member]
Income Tax Authority [Line Items]
Prepaid income taxes	10.9			$ 6.1
State and Local [Member]
Income Tax Authority [Line Items]
Prepaid income taxes	$ 1.1			$ 0.9
Scenario, Forecast [Member]
Income Tax Authority [Line Items]
Federal statutory income tax rate		21.00%	28.10%