Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent	24.50%
Deferred Tax Assets, Valuation Allowance	$ 4.5		$ 4.0	$ 3.6
Income (Loss) from Continuing Operations before Income Taxes, Domestic			$ (24.7)	$ (9.7)	$ 16.5
Deferred Tax Liabilities, Net	5.5
Deferred Tax Liabilities, Unrealized Gains on Trading Securities	2.3
Income Tax Expense (Benefit)	$ 25.5	$ 2.1
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	137.00%	25.00%
Deferred Income Tax Expense (Benefit)	$ 8.9
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	$ 12.0