Available-for-Sale and Held-to-Maturity Securities (Schedule of Gross Unrealized Losses and Estimated Fair Value by Length of Time) (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	$ (1,159)
Available-for-sale Securities, Estimated fair value, Less than 12 months	56,408
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(186,073)
Available-for-sale Securities, Estimated fair value, 12 months or more	1,415,189
Available-for-sale Securities, Gross unrealized losses, Total	(187,232)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	1,471,597
U.S. Government Agency 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)
Available-for-sale Securities, Estimated fair value, Less than 12 months	442
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(174)
Available-for-sale Securities, Estimated fair value, 12 months or more	1,767
Available-for-sale Securities, Gross unrealized losses, Total	(175)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	2,209
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	(96)
Available-for-sale Securities, Estimated fair value, Less than 12 months	6,526
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(57,683)
Available-for-sale Securities, Estimated fair value, 12 months or more	536,471
Available-for-sale Securities, Gross unrealized losses, Total	(57,779)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	542,997
Mortgage-Backed Securities [Member] \| Agency 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	(240)
Available-for-sale Securities, Estimated fair value, Less than 12 months	14,817
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(123,153)
Available-for-sale Securities, Estimated fair value, 12 months or more	698,787
Available-for-sale Securities, Gross unrealized losses, Total	(123,393)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	713,604
Mortgage-Backed Securities [Member] \| Commercial [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	0
Available-for-sale Securities, Estimated fair value, Less than 12 months	0
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(3,252)
Available-for-sale Securities, Estimated fair value, 12 months or more	66,854
Available-for-sale Securities, Gross unrealized losses, Total	(3,252)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	66,854
Mortgage-Backed Securities [Member] \| Non Agency Mortgage 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	0
Available-for-sale Securities, Estimated fair value, Less than 12 months	0
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(11)
Available-for-sale Securities, Estimated fair value, 12 months or more	248
Available-for-sale Securities, Gross unrealized losses, Total	(11)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	248
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	(822)
Available-for-sale Securities, Estimated fair value, Less than 12 months	34,623
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(1,800)
Available-for-sale Securities, Estimated fair value, 12 months or more	111,062
Available-for-sale Securities, Gross unrealized losses, Total	(2,622)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	$ 145,685

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