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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 | Dec. 31, 2016 | Dec. 31, 2015
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Schedule Of Debt Securities At Amortized Cost And Fair Value Basis [Line Items] |  |  |
Available-for-sale Securities, debt maturities, Amortized Cost |  | $ 3,190,090 |
Available-for-sale Securities, debt maturities, within one year, Fair Value | [1] | 23,961 |
Available-for-sale Securities, debt maturities, after five through ten years, fair value | [1] | 895,833 |
Availably-for-sale Securities, debt maturities, after ten years, Fair Value | [1] | 1,583,240 |
Available-for-sale Securities, debt maturities, Fair Value | [1] | 3,181,313 |
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost |  | 312,069 |
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost |  | 2,626,677 |
Held-to-maturity Securities, Amortized cost | [2] | 3,038,405 | $ 1,855,399
Held-to-maturity Securities, debt maturities, Fair Value | [2] | 3,040,554 | $ 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 |  | 23,947 |
Available-for-sale Securities, debt maturities, after one year through three years, Amortized Cost |  | 271,872 |
Available-for-sale Securities, debt maturities, after three year through five years, Amortized Cost |  | 409,576 |
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost |  | 840,487 |
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost |  | 1,224,021 |
Available-for-sale Securities, debt maturities, within one year, Fair Value |  | 23,952 |
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value |  | 272,292 |
Available-for-sale Securities, debt maturities, after three year through five years, Fair Value |  | 405,986 |
Available-for-sale Securities, debt maturities, after five through ten years, fair value |  | 840,590 |
Availably-for-sale Securities, debt maturities, after ten years, Fair Value |  | 1,225,096 |
Held-to-maturity Securities, debt maturities, after one year through three years, Amortized Cost |  | 40,078 |
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost |  | 141,576 |
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost |  | 1,228,724 |
Held-to-maturity Securities, debt maturities, after one year through three years, Fair Value |  | 40,108 |
Held-to-maturity Securities, debt maturities, after five through ten years, Fair Value |  | 141,973 |
Held-to-maturity Securities, debt maturities, after ten years, Fair Value |  | 1,231,173 |
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 |  | 9 |
Available-for-sale Securities, debt maturities, after five through ten years, Amortized Cost |  | 58,967 |
Availably-for-sale Securities, debt maturities, after ten years, Amortized Cost |  | 361,211 |
Available-for-sale Securities, debt maturities, within one year, Fair Value |  | 9 |
Available-for-sale Securities, debt maturities, after five through ten years, fair value |  | 55,245 |
Availably-for-sale Securities, debt maturities, after ten years, Fair Value |  | 358,143 |
Held-to-maturity Securities, debt maturities, after three year through five years, Amortized Cost |  | 59,581 |
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost |  | 170,493 |
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost |  | 1,397,953 |
Held-to-maturity Securities, debt maturities, after three year through five years, Fair Value |  | 61,367 |
Held-to-maturity Securities, debt maturities, after five through ten years, Fair Value |  | 169,498 |
Held-to-maturity Securities, debt maturities, after ten years, Fair Value |  | $ 1,396,435 |
[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.

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- Definition Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the fifth through tenth fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (f)(3) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803 + Details
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