Mortgage Loans - Loan Commitments and Related Derivatives Textual (Details) - Financial Services [Member] - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Interest rate lock commitments [Member]
Derivative [Line Items]
Notional amount	$ 467.6	$ 370.9
Best-efforts whole loan delivery commitments [Member]
Derivative [Line Items]
Notional amount	37.2	37.7
Hedging Instruments Related To IRLCs [Member]
Derivative [Line Items]
Notional amount	$ 385.5	$ 297.2