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Fair Value Measurements (Tables) | 6 Months Ended
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Mar. 31, 2024
Fair Value Disclosures [Abstract] |
Schedule of Fair Value of Assets Measured on Recurring Basis | The following tables present the balance and level in the fair value hierarchy of assets and liabilities that are measured at fair value on a recurring basis (with the exception of those measured using the NAV practical expedient).
| March 31, 2024
| Level 1 |  | Level 2 |  | Level 3 |  | Total
| (In thousands)
Financial Assets |  |  |  |  |  |  |
Available-for-sale securities: |  |  |  |  |  |  |
U.S. government and agency securities | $ | — |  |  | $ | 312,199 |  |  | $ | — |  |  | $ | 312,199 |
Asset-backed securities | — |  |  | 549,463 |  |  | — |  |  | 549,463 |
Municipal bonds | — |  |  | 35,061 |  |  | — |  |  | 35,061 |
Corporate debt securities | — |  |  | 249,743 |  |  | — |  |  | 249,743 |
Mortgage-backed securities |  |  |  |  |  |  |
Agency pass-through certificates | — |  |  | 1,291,648 |  |  | — |  |  | 1,291,648 |
Total available-for-sale securities | — |  |  | 2,438,114 |  |  | — |  |  | 2,438,114 |
Loans held for sale | — |  |  | 2,993,658 |  |  | — |  |  | 2,993,658 |
Derivatives: |  |  |  |  |  |  |
Client swap program hedges | — |  |  | 63,264 |  |  | — |  |  | 63,264 |
Commercial loan fair value hedges | — |  |  | 2,509 |  |  | — |  |  | 2,509 |
Mortgage loan fair value hedges | — |  |  | 56,093 |  |  | — |  |  | 56,093 |
Borrowings cash flow hedges | — |  |  | 154,588 |  |  | — |  |  | 154,588 |
Total financial assets | $ | — |  |  | $ | 5,708,226 |  |  | $ | — |  |  | $ | 5,708,226 |
Financial Liabilities |  |  |  |  |  |  |
Client swap program hedges | $ | — |  |  | $ | 64,020 |  |  | $ | — |  |  | $ | 64,020 |
Total financial liabilities | $ | — |  |  | $ | 64,020 |  |  | $ | — |  |  | $ | 64,020 |
| September 30, 2023
| Level 1 |  | Level 2 |  | Level 3 |  | Total
| (In thousands)
Financial Assets |  |  |  |  |  |  |
Available-for-sale securities: |  |  |  |  |  |  |
U.S. government and agency securities | $ | — |  |  | $ | 217,053 |  |  | $ | — |  |  | $ | 217,053 |
Asset-backed securities | — |  |  | 588,016 |  |  |  |  | 588,016 |
Municipal bonds | — |  |  | 34,662 |  |  | — |  |  | 34,662 |
Corporate debt securities | — |  |  | 242,522 |  |  | — |  |  | 242,522 |
Mortgage-backed securities |  |  |  |  |  |  |
Agency pass-through certificates | — |  |  | 912,844 |  |  | — |  |  | 912,844 |
Total available-for-sale securities | — |  |  | 1,995,097 |  |  | — |  |  | 1,995,097 |
Client swap program hedges | — |  |  | 78,797 |  |  | — |  |  | 78,797 |
Commercial loan fair value hedges | — |  |  | 3,405 |  |  | — |  |  | 3,405 |
Mortgage loan fair value hedges | — |  |  | 46,396 |  |  | — |  |  | 46,396 |
Borrowings cash flow hedges | — |  |  | 184,373 |  |  | — |  |  | 184,373 |
Total financial assets | $ | — |  |  | $ | 2,308,068 |  |  | $ | — |  |  | $ | 2,308,068 |
Financial Liabilities |  |  |  |  |  |  |
Client swap program hedges | $ | — |  |  | $ | 79,668 |  |  | $ | — |  |  | $ | 79,668 |
Total financial liabilities | $ | — |  |  | $ | 79,668 |  |  | $ | — |  |  | $ | 79,668 |
Schedule of Fair Value of Assets Measured on Nonrecurring Basis | The following tables present the aggregated balance of assets that were measured at fair value on a nonrecurring basis at March 31, 2024 and March 31, 2023, and the total gains (losses) resulting from those fair value adjustments during the respective periods. The estimated fair value measurements are shown gross of estimated selling costs.
| March 31, 2024 |  | Three Months Ended March 31, 2024 |  | Six Months Ended March 31, 2024
| Level 1 |  | Level 2 |  | Level 3 |  | Total |  | Total Gains (Losses)
| (In thousands) |  | (In thousands)
Loans (1) | $ | — |  |  | $ | — |  |  | $ | 781 |  |  | $ | 781 |  |  | $ | (168) |  |  | $ | (325) |
Real estate owned (2) | — |  |  | — |  |  | 1,360 |  |  | 1,360 |  |  | (1,875) |  |  | (1,875) |
Balance at end of period | $ | — |  |  | $ | — |  |  | $ | 2,141 |  |  | $ | 2,141 |  |  | $ | (2,043) |  |  | $ | (2,200) |
(1)The gains (losses) represent re-measurements of collateral-dependent loans. (2)The gains (losses) represent aggregate write-downs and charge-offs on real estate owned.
| March 31, 2023 |  | Three Months Ended March 31, 2023 |  | Six Months Ended March 31, 2023
| Level 1 |  | Level 2 |  | Level 3 |  | Total |  | Total Gains (Losses)
| (In thousands) |  | (In thousands)
Loans (1) | $ | — |  |  | $ | — |  |  | $ | 3,313 |  |  | $ | 3,313 |  |  | $ | (6,120) |  |  | $ | (6,243) |
Real estate owned (2) | — |  |  | — |  |  | 372 |  |  | 372 |  |  | 22 |  |  | 22 |
Balance at end of period | $ | — |  |  | $ | — |  |  | $ | 3,685 |  |  | $ | 3,685 |  |  | $ | (6,098) |  |  | $ | (6,221) |
(1)The gains (losses) represent re-measurements of collateral-dependent loans. (2)The gains (losses) represent aggregate write-downs and charge-offs on real estate owned.
Schedule of Fair Value of Financial Instruments by Balance Sheet Grouping | Although management is not aware of any factors that would materially affect the estimated fair value amounts presented below, such amounts have not been comprehensively revalued for purposes of these financial statements since the dates shown, and therefore, estimates of fair value subsequent to those dates may differ significantly from the amounts presented below.
|  |  |  | March 31, 2024 |  | September 30, 2023
|  | Level in Fair Value Hierarchy |  | Carrying Amount |  | Estimated Fair Value |  | Carrying Amount |  | Estimated Fair Value
|  |  |  | ($ in thousands)
Financial assets |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  | 1 |  | $ | 1,505,771 |  |  | $ | 1,505,771 |  |  | $ | 980,649 |  |  | $ | 980,649 |
Available-for-sale securities |  |  |  |  |  |  |  |  |  |
U.S. government and agency securities |  | 2 |  | 312,199 |  |  | 312,199 |  |  | 217,053 |  |  | 217,053 |
Asset-backed securities |  | 2 |  | 549,463 |  |  | 549,463 |  |  | 588,016 |  |  | 588,016 |
Municipal bonds |  | 2 |  | 35,061 |  |  | 35,061 |  |  | 34,662 |  |  | 34,662 |
Corporate debt securities |  | 2 |  | 249,743 |  |  | 249,743 |  |  | 242,522 |  |  | 242,522 |
Mortgage-backed securities |  |  |  |  |  |  |  |  |  |
Agency pass-through certificates |  | 2 |  | 1,291,648 |  |  | 1,291,648 |  |  | 912,844 |  |  | 912,844 |
Total available-for-sale securities |  |  |  | 2,438,114 |  |  | 2,438,114 |  |  | 1,995,097 |  |  | 1,995,097 |
Held-to-maturity securities |  |  |  |  |  |  |  |  |  |
Mortgage-backed securities |  |  |  |  |  |  |  |  |  |
Agency pass-through certificates |  | 2 |  | 457,882 |  |  | 407,461 |  |  | 423,586 |  |  | 355,188 |
Total held-to-maturity securities |  |  |  | 457,882 |  |  | 407,461 |  |  | 423,586 |  |  | 355,188 |
Loans receivable |  | 3 |  | 20,795,259 |  |  | 20,245,348 |  |  | 17,476,550 |  |  | 16,559,758 |
Loans held for sale |  | 2 |  | 2,993,658 |  |  | 2,993,658 |  |  | — |  |  | — |
FHLB stock |  | 2 |  | 160,817 |  |  | 160,817 |  |  | 126,820 |  |  | 126,820 |
Other assets - client swap program hedges |  | 2 |  | 63,264 |  |  | 63,264 |  |  | 78,797 |  |  | 78,797 |
Other assets - commercial fair value loan hedges |  | 2 |  | 2,509 |  |  | 2,509 |  |  | 3,405 |  |  | 3,405 |
Other assets - mortgage loan fair value hedges |  | 2 |  | 56,093 |  |  | 56,093 |  |  | 46,396 |  |  | 46,396 |
Other assets - borrowings cash flow hedges |  | 2 |  | 154,588 |  |  | 154,588 |  |  | 184,373 |  |  | 184,373 |
Financial liabilities |  |  |  |  |  |  |  |  |  |
Time deposits |  | 2 |  | 9,000,911 |  |  | 9,037,254 |  |  | 5,305,016 |  |  | 5,232,689 |
Borrowings |  | 2 |  | 5,345,518 |  |  | 5,320,188 |  |  | 3,650,000 |  |  | 3,653,229 |
Junior subordinated deferrable interest debentures |  | 3 |  | 50,254 |  |  | 50,320 |  |  | — |  |  | — |
Senior Debt |  | 2 |  | 93,729 |  |  | 93,373 |  |  | — |  |  | — |
Other liabilities - client swap program hedges |  | 2 |  | 64,020 |  |  | 64,020 |  |  | 79,668 |  |  | 79,668 |
Schedule of Reconciliation of Amortized Cost to Fair Value of Available-for-Sale and Held-to-Maturity Securities | The following tables provide details about the amortized cost and fair value of available-for-sale and held-to-maturity securities.
| March 31, 2024
| Amortized Cost |  | Gross Unrealized |  | Fair Value |  | Yield
| Gains |  | Losses |
| ($ in thousands)
Available-for-sale securities |  |  |  |  |  |  |  |  |
U.S. government and agency securities due |  |  |  |  |  |  |  |  |
Within 1 year | $ | 8,692 |  |  | $ | 5 |  |  | $ | (7) |  |  | $ | 8,690 |  |  | 5.83 | %
1 to 5 years | 5,699 |  |  | 4 |  |  | (264) |  |  | 5,439 |  |  | 2.89 |
5 to 10 years | 162,027 |  |  | 524 |  |  | (90) |  |  | 162,461 |  |  | 6.01 |
Over 10 years | 135,961 |  |  | 37 |  |  | (389) |  |  | 135,609 |  |  | 6.32 |
Asset-backed securities |  |  |  |  |  |  |  |  |
1 to 5 years | 13,249 |  |  | — |  |  | (397) |  |  | 12,852 |  |  | 6.08 |
5 to 10 years | 24,380 |  |  | 65 |  |  | — |  |  | 24,445 |  |  | 6.23 |
Over 10 years | 513,964 |  |  | 1,251 |  |  | (3,049) |  |  | 512,166 |  |  | 6.30 |
Corporate debt securities due |  |  |  |  |  |  |  |  |
Within 1 year | 8,100 |  |  | — |  |  | (1) |  |  | 8,099 |  |  | 3.35 |
1 to 5 years | 144,034 |  |  | 1,140 |  |  | (845) |  |  | 144,329 |  |  | 5.20 |
5 to 10 years | 112,625 |  |  | — |  |  | (15,310) |  |  | 97,315 |  |  | 3.87 |
Municipal bonds due |  |  |  |  |  |  |  |  |
5 to 10 years | 5,705 |  |  | — |  |  | (265) |  |  | 5,440 |  |  | 3.00 |
Over 10 years | 29,812 |  |  | 3 |  |  | (194) |  |  | 29,621 |  |  | 5.85 |
Mortgage-backed securities |  |  |  |  |  |  |  |  |
Agency pass-through certificates | 1,358,888 |  |  | 1,232 |  |  | (68,472) |  |  | 1,291,648 |  |  | 3.85 |
| 2,523,136 |  |  | 4,261 |  |  | (89,283) |  |  | 2,438,114 |  |  | 4.76 |
Held-to-maturity securities |  |  |  |  |  |  |  |  |
Mortgage-backed securities |  |  |  |  |  |  |  |  |
Agency pass-through certificates | 457,882 |  |  | 23 |  |  | (50,444) |  |  | 407,461 |  |  | 3.17 |
| 457,882 |  |  | 23 |  |  | (50,444) |  |  | 407,461 |  |  | 3.17 |
| $ | 2,981,018 |  |  | $ | 4,284 |  |  | $ | (139,727) |  |  | $ | 2,845,575 |  |  | 4.47 | %
| September 30, 2023
| Amortized Cost |  | Gross Unrealized |  | Fair Value |  | Yield
| Gains | Losses |
| ($ in thousands)
Available-for-sale securities |  |  |  |  |  |  |  |  |
U.S. government and agency securities due |  |  |  |  |  |  |  |  |
Within 1 year | $ | 3,501 |  |  | $ | — |  |  | $ | (36) |  |  | $ | 3,465 |  |  | 6.06 | %
1 to 5 years | 18,894 |  |  | — |  |  | (563) |  |  | 18,331 |  |  | 4.70 |
5 to 10 years | 87,922 |  |  | 177 |  |  | — |  |  | 88,099 |  |  | 5.76 |
Over 10 years | 106,340 |  |  | 831 |  |  | (13) |  |  | 107,158 |  |  | 5.84 |
Asset-backed securities |  |  |  |  |  |  |  |  |
1 to 5 years | 18,579 |  |  | — |  |  | (715) |  |  | 17,864 |  |  | 6.06 |
5 to 10 years | 36,875 |  |  | 2 |  |  | (99) |  |  | 36,778 |  |  | 6.11 |
Over 10 years | 539,911 |  |  | 578 |  |  | (7,115) |  |  | 533,374 |  |  | 6.35 |
Corporate debt securities due |  |  |  |  |  |  |  |  |
1 to 5 years | 151,893 |  |  | 895 |  |  | (1,787) |  |  | 151,001 |  |  | 5.14 |
5 to 10 years | 113,221 |  |  | — |  |  | (21,700) |  |  | 91,521 |  |  | 3.87 |
Municipal bonds due |  |  |  |  |  |  |  |  |
5 to 10 years | 5,720 |  |  | — |  |  | (701) |  |  | 5,019 |  |  | 3.00 |
Over 10 years | 29,832 |  |  | 361 |  |  | (550) |  |  | 29,643 |  |  | 5.85 |
Mortgage-backed securities |  |  |  |  |  |  |  |  |
Agency pass-through certificates | 1,005,928 |  |  | 66 |  |  | (93,150) |  |  | 912,844 |  |  | 3.39 |
| 2,118,616 |  |  | 2,910 |  |  | (126,429) |  |  | 1,995,097 |  |  | 4.64 |
Held-to-maturity securities |  |  |  |  |  |  |  |  |
Mortgage-backed securities |  |  |  |  |  |  |  |  |
Agency pass-through certificates | 423,586 |  |  | — |  |  | (68,398) |  |  | 355,188 |  |  | 2.88 |
| 423,586 |  |  | — |  |  | (68,398) |  |  | 355,188 |  |  | 2.88 |
| $ | 2,542,202 |  |  | $ | 2,910 |  |  | $ | (194,827) |  |  | $ | 2,350,285 |  |  | 4.35 | %
Schedule of Debt Securities, Available-for-Sale | The following tables show the gross unrealized losses and fair value of securities as of March 31, 2024 and September 30, 2023, by length of time that individual securities in each category have been in a continuous loss position. There were 253 and 231 securities with an unrealized loss as of March 31, 2024 and September 30, 2023, respectively.
March 31, 2024 | Less than 12 months |  | 12 months or more |  | Total
| Unrealized Gross Losses |  | Fair Value |  | Unrealized Gross Losses |  | Fair Value |  | Unrealized Gross Losses |  | Fair Value
| (In thousands) |  |
Available-for-sale securities |  |  |  |  |  |  |  |  |  |  |
Corporate debt securities | $ | (214) |  |  | $ | 19,779 |  |  | $ | (15,942) |  |  | $ | 154,496 |  |  | $ | (16,156) |  |  | $ | 174,275 |
Municipal bonds | — |  |  | — |  |  | (458) |  |  | 15,059 |  |  | (458) |  |  | 15,059 |
Asset-backed securities | (485) |  |  | 110,515 |  |  | (3,712) |  |  | 247,943 |  |  | (4,197) |  |  | 358,458 |
Mortgage-backed securities | (734) |  |  | 208,696 |  |  | (67,738) |  |  | 719,962 |  |  | (68,472) |  |  | 928,658 |
| (1,433) |  |  | 338,990 |  |  | (87,850) |  |  | 1,137,460 |  |  | (89,283) |  |  | 1,476,450 |
Held-to-maturity securities |  |  |  |  |  |  |  |  |  |  |
Mortgage-backed securities | (2) |  |  | 263 |  |  | (50,442) |  |  | 354,819 |  |  | (50,444) |  |  | 355,082 |
| $ | (1,435) |  |  | $ | 339,253 |  |  | $ | (138,292) |  |  | $ | 1,492,279 |  |  | $ | (139,727) |  |  | $ | 1,831,532 |
September 30, 2023 | Less than 12 months |  | 12 months or more |  | Total
| Unrealized Gross Losses |  | Fair Value |  | Unrealized Gross Losses |  | Fair Value |  | Unrealized Gross Losses |  | Fair Value
| (In thousands) |  |
Available-for-sale securities |  |  |  |  |  |  |  |  |  |  |
Corporate debt securities | $ | — |  |  | $ | — |  |  | $ | (23,487) |  |  | $ | 167,452 |  |  | $ | (23,487) |  |  | $ | 167,452 |
Municipal bonds due | — |  |  | — |  |  | (1,250) |  |  | 14,302 |  |  | (1,250) |  |  | 14,302 |
U.S. government and agency securities | (13) |  |  | 14,917 |  |  | (599) |  |  | 21,795 |  |  | (612) |  |  | 36,712 |
Asset-backed securities | (2,142) |  |  | 86,800 |  |  | (5,788) |  |  | 445,454 |  |  | (7,930) |  |  | 532,254 |
Mortgage-backed securities | (2,030) |  |  | 142,235 |  |  | (91,120) |  |  | 744,010 |  |  | (93,150) |  |  | 886,245 |
| (4,185) |  |  | 243,952 |  |  | (122,244) |  |  | 1,393,013 |  |  | (126,429) |  |  | 1,636,965 |
Held-to-maturity securities |  |  |  |  |  |  |  |  |  |  |
Mortgage-backed securities | (15) |  |  | 1,424 |  |  | (68,383) |  |  | 353,764 |  |  | (68,398) |  |  | 355,188 |
| $ | (4,200) |  |  | $ | 245,376 |  |  | $ | (190,627) |  |  | $ | 1,746,777 |  |  | $ | (194,827) |  |  | $ | 1,992,153 |

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- Definition Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-9 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aaa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 + Details
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- Definition Tabular disclosure of assets and liabilities by class, including financial instruments measured at fair value that are classified in shareholders' equity, if any, that are measured at fair value on a nonrecurring basis in periods after initial recognition (for example, impaired assets). Disclosures may include, but are not limited to: (a) the fair value measurements recorded and the reasons for the measurements and (b) the level within the fair value hierarchy in which the fair value measurements are categorized in their entirety (levels 1, 2, 3). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb) -SubTopic 10 -Topic 820 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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- Definition Reconciliation of Amortized Cost to Fair Value, Available-for-sale Securities and Held-to-maturity Securities [Table Text Block] + References No definition available. + Details
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