Available-for-Sale and Held-to-Maturity Securities (Schedule of Amortized Cost and Fair Values of Available for Sale Securities and Held to Maturity Securities) (Details) - USD ($) $ in Thousands		Mar. 31, 2024		Dec. 31, 2023
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 1,687,144		$ 1,727,630
Available for sale securities, Gross Unrealized Gains	[1]	70		6
Available-for-sale Securities, Gross unrealized losses	[1]	(187,232)		(175,950)
Available-for-sale securities, Fair Value		1,499,982	[2]	1,551,686
Held-to-maturity securities, at amortized cost	[3]	5,793,750		5,888,798
Held-to-maturity Securities, Gross unrealized gains	[3]	10,699		6,387	[1]
Held-to-maturity Securities, Gross unrealized losses	[3]	(11,503)		(43,009)	[1]
Held-to-maturity securities, Estimated fair value		5,792,946		5,852,176	[3]
U.S. Government Agency Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		2,384		2,376
Available for sale securities, Gross Unrealized Gains	[1]	0		5
Available-for-sale Securities, Gross unrealized losses	[1]	(175)		(162)
Available-for-sale securities, Fair Value		2,209		2,219
State And Municipal Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		2,350		2,350
Available for sale securities, Gross Unrealized Gains	[1]	0		1
Available-for-sale Securities, Gross unrealized losses	[1]	0		0
Available-for-sale securities, Fair Value		2,350		2,351
Agency Mortgage-Backed Securities [Member] | Agency Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		837,331		855,456
Available for sale securities, Gross Unrealized Gains	[1]	1		0
Available-for-sale Securities, Gross unrealized losses	[1]	(123,393)		(109,286)
Available-for-sale securities, Fair Value		713,939	[2]	746,170
Agency Mortgage-Backed Securities [Member] | Commercial [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		70,106		70,326
Available for sale securities, Gross Unrealized Gains	[1]	0		0
Available-for-sale Securities, Gross unrealized losses	[1]	(3,252)		(3,655)
Available-for-sale securities, Fair Value		66,854	[2]	66,671
Agency Mortgage-Backed Securities [Member] | Non-Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		259		274
Available for sale securities, Gross Unrealized Gains	[1]	0		0
Available-for-sale Securities, Gross unrealized losses	[1]	(11)		(13)
Available-for-sale securities, Fair Value		248	[2]	261
Corporate Fixed Income Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		600,776		615,131
Available for sale securities, Gross Unrealized Gains	[1]	0		0
Available-for-sale Securities, Gross unrealized losses	[1]	(57,779)		(58,970)
Available-for-sale securities, Fair Value		542,997		556,161
Asset-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized Cost		173,938		181,717
Available for sale securities, Gross Unrealized Gains	[1]	69		0
Available-for-sale Securities, Gross unrealized losses	[1]	(2,622)		(3,864)
Available-for-sale securities, Fair Value		171,385	[2]	$ 177,853
Held-to-maturity securities, at amortized cost	[2]	$ 5,793,750

[1] Unrealized gains/(losses) related to available-for-sale securities are reported in accumulated other comprehensive income.

[2] Due to the immaterial amount of income recognized on tax-exempt securities, yields were not calculated on a tax-equivalent basis.

[3] 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.