On-Balance Sheet Derivative Instruments And Hedging Activities (Schedule Of Outstanding Derivative Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2011
Other Assets [Member] | Asset Derivatives [Member] | Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Asset Derivatives Fair Value	$ 2,397	$ 15,936
Other Assets [Member] | Asset Derivatives [Member] | Not Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Asset Derivatives Fair Value	35,263	20,789
Other Assets [Member] | Asset Derivatives [Member] | Interest Rate Contracts [Member] | Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Asset Derivatives Fair Value	2,397	15,936
Other Assets [Member] | Asset Derivatives [Member] | Interest Rate Contracts [Member] | Not Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Asset Derivatives Fair Value	23,994	14,987
Other Assets [Member] | Asset Derivatives [Member] | Written And Purchased Options [Member] | Not Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Asset Derivatives Fair Value	11,269	5,802
Other Liabilities [Member] | Liability Derivatives [Member] | Not Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Liability Derivatives Fair Value	35,262	20,789
Other Liabilities [Member] | Liability Derivatives [Member] | Interest Rate Contracts [Member] | Not Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Liability Derivatives Fair Value	23,993	14,986
Other Liabilities [Member] | Liability Derivatives [Member] | Written And Purchased Options [Member] | Not Designated As Hedging Instruments [Member]
On Balance Sheet Derivative Instruments And Hedging Activities [Line Items]
Liability Derivatives Fair Value	$ 11,269	$ 5,802