Derivatives (Derivatives Associated With Capital Markets Trading Activities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2011
Customer Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	$ 1,502,356	$ 1,579,996
Assets	113,429	55,979
Liabilities	2,749	4,968
Offsetting Upstream Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	1,502,356	1,579,996
Assets	2,749	4,968
Liabilities	113,429	55,979
Option Contracts Purchased [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures		8,000
Assets, Forwards and Futures		14
Forwards And Futures Purchased [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures	4,222,885	3,862,658
Assets, Forwards and Futures	2,737	7,117
Liabilities, Forwards and Futures	4,716	1,912
Forwards And Futures Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional, Forwards and Futures	4,557,546	4,251,527
Assets, Forwards and Futures	4,454	2,247
Liabilities, Forwards and Futures	$ 4,667	$ 9,689