Available-for-Sale Securities (Tables)
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6 Months Ended |
Jun. 30, 2026 |
| Debt Securities, Available-for-sale [Line Items] |
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| Schedule of Available-for-sale Securities Reconciliation [Table Text Block] |
Available-for-sale securities as of June 30, 2026 were as follows (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Estimated Fair Value | | | | | | | | | | | | | | | | | | | | | | | | | | GSE debentures | $ | 538,687 | | | $ | 5,130 | | | $ | — | | | $ | 543,817 | | | | | | | | | | | | | | | | | | | | | | | | | | | GSE commercial MBS | 16,971,160 | | | 240,030 | | | 3,370 | | | 17,207,820 | | | Total | $ | 17,509,847 | | | $ | 245,160 | | | $ | 3,370 | | | $ | 17,751,637 | |
Available-for-sale securities as of December 31, 2025 were as follows (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Estimated Fair Value | | | | | | | | | | | | | | | | | | GSE debentures | $ | 1,489,642 | | | $ | 9,189 | | | $ | — | | | $ | 1,498,831 | | | | | | | | | | | | | | | | | | GSE commercial MBS | 17,635,403 | | | 176,702 | | | 2,744 | | | 17,809,361 | | | Total | $ | 19,125,045 | | | $ | 185,891 | | | $ | 2,744 | | | $ | 19,308,192 | |
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| Schedule of Unrealized Loss on Investments [Table Text Block] |
The following table summarizes (in thousands) the available-for-sale securities with unrealized losses (all of which were GSE CMBS) as of June 30, 2026 and December 31, 2025. The unrealized losses are aggregated by length of time that individual securities have been in a continuous loss position. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Less than 12 Months | | 12 Months or More | | Total | | | Estimated Fair Value | | Gross Unrealized Losses | | Estimated Fair Value | | Gross Unrealized Losses | | Estimated Fair Value | | Gross Unrealized Losses | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | June 30, 2026 | | $ | 146,624 | | | $ | 1,469 | | | $ | 36,059 | | | $ | 1,901 | | | $ | 182,683 | | | $ | 3,370 | | | | | | | | | | | | | | | | December 31, 2025 | | $ | 207,012 | | | $ | 636 | | | $ | 88,049 | | | $ | 2,108 | | | $ | 295,061 | | | $ | 2,744 | |
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| Investments Classified by Contractual Maturity Date [Table Text Block] |
The amortized cost and estimated fair value of available-for-sale securities by contractual maturity at June 30, 2026 and December 31, 2025 are presented below (in thousands). | | | | | | | | | | | | | | | | | | | | | | | | | | | | | June 30, 2026 | | December 31, 2025 | | Maturity | | Amortized Cost | | Estimated Fair Value | | Amortized Cost | | Estimated Fair Value | | | Debentures | | | | | | | | | | Due in one year or less | | $ | 301,435 | | | $ | 302,725 | | | $ | 1,035,186 | | | $ | 1,037,965 | | | Due after one year through five years | | 237,252 | | | 241,092 | | | 440,776 | | | 446,564 | | | Due after five years through ten years | | — | | | — | | | 13,680 | | | 14,302 | | | | | | | | | | | | | 538,687 | | | 543,817 | | | 1,489,642 | | | 1,498,831 | | | GSE CMBS | | 16,971,160 | | | 17,207,820 | | | 17,635,403 | | | 17,809,361 | | | Total | | $ | 17,509,847 | | | $ | 17,751,637 | | | $ | 19,125,045 | | | $ | 19,308,192 | |
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