Schedule II - Condensed Financial Information of Registrant - Condensed Balance Sheet of Registrant (Details) - USD ($) $ in Millions	Mar. 31, 2018	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016
ASSETS
Cash and cash equivalents	$ 758.8	$ 270.1	$ 294.6	$ 465.2
Receivables, net	337.6	266.0
Assets, Current	3,805.3	30,036.1
Property, plant and equipment, net	504.5	503.9
Total assets	8,240.3	35,849.7
LIABILITIES AND EQUITY
Interest Payable, Current	62.6	78.0
Liabilities, Current	1,222.5	27,645.0
Long-term debt	5,404.2	5,801.9
Deferred tax liabilities	285.8	493.2
Other long-term liabilities	101.1	26.2
Total liabilities	6,896.6	33,902.8
Stockholders’ equity:
Common stock	2.1	2.0
Accumulated deficit	(455.6)	(925.9)
Accumulated other comprehensive (loss) income	(125.3)	309.0
Total permanent equity	1,343.7	1,946.9
Total liabilities and equity	$ 8,240.3	$ 35,849.7