Available-for-Sale and Held-to-Maturity Securities (Schedule of Amortized Cost of Held-to-Maturity Securities by Credit Quality Indicator) (Details) - USD ($) $ in Thousands		Mar. 31, 2025	Dec. 31, 2024
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity securities, at amortized cost	[1]	$ 6,716,753	$ 6,524,954
Asset-Backed Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity securities, at amortized cost		6,716,753
Asset-Backed Securities [Member] | AAA [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity securities, at amortized cost		3,570,037
Asset-Backed Securities [Member] | AA [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity securities, at amortized cost		3,146,211
Asset-Backed Securities [Member] | C [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity securities, at amortized cost		$ 505

[1] 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.