Available-For-Sale And Held-To-Maturity Securities (Schedule Of Gross Unrealized Losses And The Estimated Fair Value By Length Of Time In A Loss Position) (Details) $ in Thousands	Mar. 31, 2021 USD ($)
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	$ (13,952)
Available-for-sale Securities, Estimated fair value, Less than 12 months	685,984
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(2,719)
Available-for-sale Securities, Estimated fair value, 12 months or more	150,571
Available-for-sale Securities, Gross unrealized losses, Total	(16,671)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	836,555
Commercial
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(30)
Available-for-sale Securities, Estimated fair value, Less than 12 months	10,416
Available-for-sale Securities, Gross unrealized losses, Total	(30)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	10,416
Agency Mortgage-Backed Securities [Member] \| Agency Securities
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(8,814)
Available-for-sale Securities, Estimated fair value, Less than 12 months	489,231
Available-for-sale Securities, Gross unrealized losses, Total	(8,814)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	489,231
Corporate Fixed Income Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(3,841)
Available-for-sale Securities, Estimated fair value, Less than 12 months	143,201
Available-for-sale Securities, Gross unrealized losses, Total	(3,841)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	143,201
Asset-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(1,267)
Available-for-sale Securities, Estimated fair value, Less than 12 months	43,136
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(2,719)
Available-for-sale Securities, Estimated fair value, 12 months or more	150,571
Available-for-sale Securities, Gross unrealized losses, Total	(3,986)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	$ 193,707

Schedule of available for sale and held to maturity securities.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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