Summary of Significant Accounting Policies - Schedule of Cash and Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 492.1	$ 452.6	$ 474.8	$ 558.4
Restricted cash	26.3	9.6	10.6	10.3
Cash, cash equivalents and restricted cash	$ 518.4	$ 462.2	$ 485.4	$ 568.7