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Investment Securities - Investments by Contractual Maturity Date (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Sep. 30, 2023
--- | --- | ---
Amortized Cost, Available-for-sale securities |  |
Amortized cost | $ 2,616,877 | $ 2,118,616
Gross Unrealized Gains / Losses, Available-for-sale securities |  |
Gross unrealized gains | 10,531 | 2,910
Gross unrealized loss | (54,699) | (126,429)
Fair Value, Available-for-sale securities |  |
Available-for-sale securities, at fair value | $ 2,572,709 | $ 1,995,097
Yield, Available-for-sale securities |  |
Yield | 4.87% | 4.64%
Amortized Cost, Held-to-maturity securities |  |
Held-to-maturity securities, amortized cost | $ 436,972 | $ 423,586
Gross Unrealized Gains / Losses, Held-to-maturity securities |  |
Gross unrealized gains | 913 | 0
Gross unrealized losses | (36,839) | (68,398)
Fair Value, Held-to-maturity securities |  |
Fair value | $ 401,046 | $ 355,188
Yield, Held-to-maturity securities |  |
Without single maturity date |  | 2.88%
Yield | 3.18% |
Investments | $ 3,053,849 | $ 2,542,202
Gross unrealized gains on investments | 11,444 | 2,910
Gross unrealized losses on investments | (91,538) | (194,827)
Total Financial Assets | $ 2,973,755 | $ 2,350,285
Yield on investments | 4.63% | 4.35%
U.S. government and agency securities due |  |
Amortized Cost, Available-for-sale securities |  |
Within 1 year | $ 4,360 | $ 3,501
1 to 5 years | 4,640 | 18,894
5 to 10 years | 166,070 | 87,922
Over 10 years | 137,799 | 106,340
Gross Unrealized Gains / Losses, Available-for-sale securities |  |
Gross unrealized gains, within 1 year | 4 | 0
Gross unrealized gains, 1 to 5 years | 2 | 0
Gross unrealized gains, 5 to 10 years | 1,230 | 177
Gross unrealized gains, over 10 years | 394 | 831
Gross unrealized losses, within 1 year | 0 | (36)
Gross unrealized losses, 1 to 5 years | (124) | (563)
Gross unrealized losses, 5 to 10 years | 0 | 0
Gross unrealized losses, over 10 years | (171) | (13)
Fair Value, Available-for-sale securities |  |
Within 1 year | 4,364 | 3,465
1 to 5 years | 4,518 | 18,331
5 to 10 years | 167,300 | 88,099
Over 10 years | $ 138,022 | $ 107,158
Yield, Available-for-sale securities |  |
Within 1 year | 5.58% | 6.06%
1 to 5 years | 2.82% | 4.70%
5 to 10 years | 5.97% | 5.76%
Over 10 years | 6.29% | 5.84%
Asset-backed securities due |  |
Amortized Cost, Available-for-sale securities |  |
1 to 5 years | $ 11,466 | $ 18,579
5 to 10 years | 9,631 | 36,875
Over 10 years | 520,756 | 539,911
Gross Unrealized Gains / Losses, Available-for-sale securities |  |
Gross unrealized gains, 1 to 5 years | 0 | 0
Gross unrealized gains, 5 to 10 years | 0 | 2
Gross unrealized gains, over 10 years | 600 | 578
Gross unrealized losses, 1 to 5 years | (284) | (715)
Gross unrealized losses, 5 to 10 years | (3) | (99)
Gross unrealized losses, over 10 years | (2,041) | (7,115)
Fair Value, Available-for-sale securities |  |
1 to 5 years | 11,182 | 17,864
5 to 10 years | 9,628 | 36,778
Over 10 years | $ 519,315 | $ 533,374
Yield, Available-for-sale securities |  |
1 to 5 years | 6.04% | 6.06%
5 to 10 years | 6.20% | 6.11%
Over 10 years | 6.15% | 6.35%
Corporate debt securities |  |
Amortized Cost, Available-for-sale securities |  |
Within 1 year | $ 45,024 | $ 0
1 to 5 years | 99,244 | 151,893
5 to 10 years | 112,029 | 113,221
Over 10 years | 50,000 |
Gross Unrealized Gains / Losses, Available-for-sale securities |  |
Gross unrealized gains, within 1 year | 0 | 0
Gross unrealized gains, 1 to 5 years | 977 | 895
Gross unrealized gains, 5 to 10 years | 0 | 0
Gross unrealized gains, over 10 years | 0 |
Gross unrealized losses, within 1 year | (367) | 0
Gross unrealized losses, 1 to 5 years | 0 | (1,787)
Gross unrealized losses, 5 to 10 years | (10,625) | (21,700)
Gross unrealized losses, over 10 years | 0 |
Fair Value, Available-for-sale securities |  |
Within 1 year | 44,657 | 0
1 to 5 years | 100,221 | 151,001
5 to 10 years | 101,404 | $ 91,521
Over 10 years | $ 50,000 |
Yield, Available-for-sale securities |  |
Within 1 year | 4.61% | 0.00%
1 to 5 years | 5.39% | 5.14%
5 to 10 years | 3.87% | 3.87%
Over 10 years | 6.85% |
Municipal bonds |  |
Amortized Cost, Available-for-sale securities |  |
5 to 10 years | $ 5,689 | $ 5,720
Over 10 years | 29,793 | 29,832
Gross Unrealized Gains / Losses, Available-for-sale securities |  |
Gross unrealized gains, 5 to 10 years | 0 | 0
Gross unrealized gains, over 10 years | 0 | 361
Gross unrealized losses, 5 to 10 years | (243) | (701)
Gross unrealized losses, over 10 years | (166) | (550)
Fair Value, Available-for-sale securities |  |
5 to 10 years | 5,446 | 5,019
Over 10 years | $ 29,627 | $ 29,643
Yield, Available-for-sale securities |  |
5 to 10 years | 3.00% | 3.00%
Over 10 years | 5.85% | 5.85%
Agency pass-through certificates |  |
Amortized Cost, Available-for-sale securities |  |
Without single maturity date | $ 1,420,376 | $ 1,005,928
Gross Unrealized Gains / Losses, Available-for-sale securities |  |
Gross unrealized gains, without single maturity date | 7,324 | 66
Gross unrealized losses, without single maturity date | (40,675) | (93,150)
Fair Value, Available-for-sale securities |  |
Without single maturity date | $ 1,387,025 | $ 912,844
Yield, Available-for-sale securities |  |
Without single maturity date | 4.09% | 3.39%
Amortized Cost, Held-to-maturity securities |  |
Without single maturity date | $ 436,972 | $ 423,586
Gross Unrealized Gains / Losses, Held-to-maturity securities |  |
Gross unrealized gains, without single maturity date | 913 | 0
Gross unrealized losses, without single maturity date | (36,839) | (68,398)
Fair Value, Held-to-maturity securities |  |
Without single maturity date | $ 401,046 | $ 355,188
Yield, Held-to-maturity securities |  |
Without single maturity date | 3.18% | 2.88%

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