Investment Securities (Schedule Of Maturities Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Investment Holdings [Line Items]
Available-for-sale Securities, Three months or less, Amortized Cost	$ 33,293
Available-for-sale Securities, Over three months through twelve months, Amortized Cost	302,638
Available-for-sale Securities, After one year through five years, Amortized Cost	1,961,957
Available-for-sale Securities, After five years through ten years, Amortized Cost	435,999
Available-for-sale Securities, After ten years, Amortized Cost	110,098
Available-for-sale Securities, Amortized Cost	2,845,944
Available-for-sale Securities, Three months or less, Fair Value	33,500
Available-for-sale Securities, Over three months through twelve months, Fair Value	305,841
Available-for-sale Securities, After one year through five years, Fair Value	1,997,457
Available-for-sale Securities, After five years through ten years, Fair Value	447,235
Available-for-sale Securities, After ten years, Fair Value	113,218
Available-for-sale Securities, Fair Value	2,899,361
Held-to-maturity Securities, Three months or less, Amortized Cost	295
Held-to-maturity Securities, Over three months through twelve months, Amortized Cost	300
Held-to-maturity Securities, After one year through five years, Amortized Cost	41
Held-to-maturity Securities, After five years through ten years, Amortized Cost	188
Held-to-maturity Securities, After ten years, Amortized Cost	4,535
Held-to-maturity Securities, Amortized Cost	5,359
Held-to-maturity Securities, Three months or less, Fair Value	296
Held-to-maturity Securities, Over three months through twelve months, Fair Value	301
Held-to-maturity Securities, After one year through five years, Fair Value	43
Held-to-maturity Securities, After five years through ten years, Fair Value	203
Held-to-maturity Securities, After ten years, Fair Value	4,521
Held-to-maturity Securities, Fair Value	5,364
Other Investments Securities [Member]
Investment Holdings [Line Items]
Available-for-sale Securities, Amortized Cost	1,959
Available-for-sale Securities, Fair Value	$ 2,110