Derivatives (Derivatives Associated with Capital Markets Trading Activities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Customer Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	$ 1,477,632	$ 1,502,356
Assets	119,866	113,429
Liabilities	1,327	2,749
Offsetting Upstream Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	1,477,632	1,502,356
Assets	1,327	2,749
Liabilities	119,866	113,429
Put Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Option Contracts	2,500
Assets, Option Contracts	5
Liabilities, Option Contracts	0
Forwards And Futures Purchased [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures	5,786,940	4,222,885
Assets, Forwards and Futures	7,541	2,737
Liabilities, Forwards and Futures	8,199	4,716
Forwards And Futures Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures	5,923,867	4,557,546
Assets, Forwards and Futures	8,090	4,454
Liabilities, Forwards and Futures	8,381	4,667
Call Option
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Option Contracts	2,500
Assets, Option Contracts	0
Liabilities, Option Contracts	$ 2