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Investment Securities - Additional Information (Detail) | 6 Months Ended |
--- | --- | ---
Jun. 30, 2022 USD ($) | Jun. 30, 2021 USD ($) | Dec. 31, 2021 USD ($)
Debt Securities, Held-to-maturity, Restricted | $ 351,000,000 |  | $ 313,900,000
Debt Securities, Available-for-sale, Restricted | $ 674,900,000 |  | 759,100,000
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total | 190 |  |
Other Investments and Securities, at Cost | $ 1,200,000 |  | 1,200,000
Federal Home Loan Bank Stock | 12,500,000 |  | 11,700,000
Amortized Cost | 956,870,000 |  | 1,045,579,000
Debt Securities, Available-for-Sale | $ 863,622,000 |  | $ 1,041,380,000
US Government-sponsored Enterprises Debt Securities [Member] |  |  |
Percent of Unrealized Losses | 97.00% |  |
Corporate Debt Securities [Member] |  |  |
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total | 4 |  | 4
Amortized Cost | $ 32,000,000 |  | $ 32,100,000
Debt Securities, Available-for-Sale | 31,000,000 |  | $ 32,900,000
Equity Securities [Member] |  |  |
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount | $ 0 | $ 0 |

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- Definition Amortized cost 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/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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