Investment Securities (Schedule Of Investments Within The Available For Sale Portfolio That Had Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2011
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	$ 101,397	$ 725,630
Less than 12 months, Unrealized Losses	(734)	(4,226)
12 months or longer, Fair Value
12 months or longer, Unrealized Losses
Total Fair Value	101,397	725,630
Total Unrealized Losses	(734)	(4,226)
Government Agency Issued Mortgage-Backed Securities ("MBS") [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value	101,397	572,326
Less than 12 months, Unrealized Losses	(734)	(3,346)
12 months or longer, Fair Value
12 months or longer, Unrealized Losses
Total Fair Value	101,397	572,326
Total Unrealized Losses	(734)	(3,346)
Government Agency Issued Collateralized Mortgage Obligations ("CMO") [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value		153,271
Less than 12 months, Unrealized Losses		(870)
12 months or longer, Fair Value
12 months or longer, Unrealized Losses
Total Fair Value		153,271
Total Unrealized Losses		(870)
Equity [Member]
Schedule of Investments [Line Items]
Less than 12 months, Fair Value		33
Less than 12 months, Unrealized Losses		(10)
12 months or longer, Fair Value
12 months or longer, Unrealized Losses
Total Fair Value		33
Total Unrealized Losses		$ (10)