Mortgage Loans - Loan Commitments and Related Derivatives (Details) - Financial Services [Member] - USD ($) $ in Millions	Jun. 30, 2016	Sep. 30, 2015
Interest rate lock commitments [Member]
Derivative [Line Items]
Notional amounts of instruments	$ 645.8	$ 370.9
Best-efforts and mandatory commitments [Member]
Derivative [Line Items]
Notional amounts of instruments	46.8	37.7
Hedging Instruments related to IRLCs [Member]
Derivative [Line Items]
Notional amounts of instruments	$ 532.4	$ 297.2