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		Sep. 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		$ 3,132,271
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	23,597
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	679,317
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,761,133
Available-for-sale Securities, debt maturities, Fair Value	[1]	3,145,267
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		181,413
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,960,129
Held-to-maturity Securities, Amortized cost	[2]	2,241,203	$ 1,855,399
Held-to-maturity Securities, debt maturities, Fair Value	[2]	2,300,092	$ 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		23,542
Available-for-sale Securities, debt maturities, after one year through three years, Amortized Cost		272,434
Available-for-sale Securities, debt maturities, after three year through five years, Amortized Cost		400,553
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost		618,997
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost		1,370,139
Available-for-sale Securities, debt maturities, within one year, Fair Value		23,575
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value		274,519
Available-for-sale Securities, debt maturities, after three year through five years, Fair Value		406,700
Available-for-sale Securities, debt maturities, after five through ten years, fair value		620,642
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		1,374,833
Held-to-maturity Securities, debt maturities, after one year through three years, Amortized Cost		40,095
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		497,361
Held-to-maturity Securities, debt maturities, after one year through three years, Fair Value		40,260
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		503,923
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		23
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost		59,143
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost		387,440
Available-for-sale Securities, debt maturities, within one year, Fair Value		23
Available-for-sale Securities, debt maturities, after five through ten years, fair value		58,674
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		386,301
Held-to-maturity Securities, debt maturities, after three year through five years, Amortized Cost		59,566
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		181,413
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,462,768
Held-to-maturity Securities, debt maturities, after three year through five years, Fair Value		63,267
Held-to-maturity Securities, debt maturities, after five through ten years, Fair Value		183,657
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		$ 1,508,985

[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.