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Investments - Additional Information (Details) $ in Thousands | 1 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Mar. 31, 2020 | Sep. 30, 2021 USD ($) security | Dec. 31, 2020 USD ($) security
Investments, Debt and Equity Securities [Abstract] |  |  |
Vertical risk retention interest | 5.00% | 5.00% |
Trading investments |  | $ 36,792 | $ 16,923
Number of mortgage-backed securities with unrealized losses | security |  | 38 | 14
Number of mortgage-backed securities | security |  | 177 | 163
Par value of mortgage-backed securities pledged to FRB |  | $ 645,000 | $ 815,000
Gain on earlier equity securities investments |  | 35,000 |
Non-marketable securities investment |  | 69,000 | 26,000
Low income housing tax credit investments |  | 69,000 | 54,000
Low income housing tax credit investments, liability for unfunded commitments |  | 33,000 | 19,000
Low income housing tax credit investments, tax credits and benefits |  | $ 1,000 | $ 6,000
Low income housing tax credit investments, expected tax benefits recognized |  | 25.00% |

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- Definition Amount of affordable housing tax credits and other tax benefits recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985 + Details
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- Definition Amount of investment in qualified affordable housing projects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985 + Details
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- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455 + Details
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