Derivatives (Derivatives Associated with Capital Markets Trading Activities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Customer Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	$ 1,439,306	$ 1,438,750
Assets	137,958	120,529
Liabilities	923	1,521
Offsetting Upstream Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	1,439,306	1,438,750
Assets	923	1,521
Liabilities	137,958	120,529
Put Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Option Contracts	5,000
Assets, Option Contracts	1
Liabilities, Option Contracts	0
Forwards And Futures Purchased [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures	4,361,583	4,732,862
Assets, Forwards and Futures	1,173	4,009
Liabilities, Forwards and Futures	10,662	5,292
Forwards And Futures Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures	4,706,866	5,079,886
Assets, Forwards and Futures	13,147	4,869
Liabilities, Forwards and Futures	$ 1,762	$ 6,799