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		Mar. 31, 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		$ 2,138,602
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	953
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	297,432
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,319,987
Available-for-sale Securities, debt maturities, Fair Value	[1]	2,125,466
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		261,778
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,726,273
Held-to-maturity Securities, Amortized cost	[2]	2,028,179	$ 1,855,399
Held-to-maturity Securities, debt maturities, Fair Value	[2]	2,064,996	$ 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		955
Available-for-sale Securities, debt maturities, after one year through three years, Amortized Cost		198,269
Available-for-sale Securities, debt maturities, after three year through five years, Amortized Cost		303,415
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost		302,503
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost		903,949
Available-for-sale Securities, debt maturities, within one year, Fair Value		953
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value		199,697
Available-for-sale Securities, debt maturities, after three year through five years, Fair Value		307,345
Available-for-sale Securities, debt maturities, after five through ten years, fair value		296,855
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		898,137
Held-to-maturity Securities, debt maturities, after one year through three years, Amortized Cost		40,128
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		497,134
Held-to-maturity Securities, debt maturities, after one year through three years, Fair Value		40,094
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		495,769
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		52
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost		547
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost		428,912
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value		52
Available-for-sale Securities, debt maturities, after five through ten years, fair value		577
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		421,850
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		261,778
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,229,139
Held-to-maturity Securities, debt maturities, after five through ten years, Fair Value		266,426
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		$ 1,262,707

[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.