Marketable Securities - Credit Quality of Held to Maturity Securities (Details) $ in Thousands	Sep. 30, 2026 USD ($)
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Total marketable securities held-to-maturity	$ 612,731
Mortgage-backed securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Total marketable securities held-to-maturity	504,740
Debt issued by the U.S. government-sponsored enterprises
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Total marketable securities held-to-maturity	107,991
AA+
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Total marketable securities held-to-maturity	612,731
AA+ \| Mortgage-backed securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Total marketable securities held-to-maturity	504,740
AA+ \| Debt issued by the U.S. government-sponsored enterprises
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Total marketable securities held-to-maturity	$ 107,991