Available-For-Sale And Held-To-Maturity Securities (Schedule Of Amortized Cost And Fair Values Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Schedule Of Debt Securities At Amortized Cost And Fair Value Basis [Line Items]
Available-for-sale Securities, debt maturities, Amortized Cost		$ 2,461,034
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	1,119
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	359,659
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,497,365
Available-for-sale Securities, debt maturities, Fair Value	[1]	2,466,706
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		251,937
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,827,839
Held-to-maturity Securities, Amortized cost	[2]	2,119,888	$ 1,855,399
Held-to-maturity Securities, debt maturities, Fair Value	[2]	2,178,218	$ 1,874,998
Excluding Mortgage Backed Securities [Member]
Schedule Of Debt Securities At Amortized Cost And Fair Value Basis [Line Items]
Available-for-sale Securities, debt maturities, within one year, Amortized Cost		1,081
Available-for-sale Securities, debt maturities, after one year through three years, Amortized Cost		271,590
Available-for-sale Securities, debt maturities, after three year through five years, Amortized Cost		327,468
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost		361,739
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost		1,098,226
Available-for-sale Securities, debt maturities, within one year, Fair Value		1,081
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value		274,003
Available-for-sale Securities, debt maturities, after three year through five years, Fair Value		334,561
Available-for-sale Securities, debt maturities, after five through ten years, fair value		359,105
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		1,097,710
Held-to-maturity Securities, debt maturities, after one year through three years, Amortized Cost		40,111
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		497,243
Held-to-maturity Securities, debt maturities, after one year through three years, Fair Value		40,265
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		500,379
Mortgage Backed Securities [Member]
Schedule Of Debt Securities At Amortized Cost And Fair Value Basis [Line Items]
Available-for-sale Securities, debt maturities, after one year through three years, Amortized Cost		38
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost		523
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost		400,369
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value		38
Available-for-sale Securities, debt maturities, after five through ten years, fair value		553
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		399,655
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		251,937
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,330,597
Held-to-maturity Securities, debt maturities, after five through ten years, Fair Value		258,896
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		$ 1,378,678

[1] Due to the immaterial amount of income recognized on tax-exempt securities, yields were not calculated on a tax-equivalent basis.

[2] Held-to-maturity securities are carried in the consolidated statements of financial condition at amortized cost, and the changes in the value of these securities, other than impairment charges, are not reported on the consolidated financial statements.