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Investments - Additional Information (Details) $ in Thousands |  | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Feb. 09, 2021 | Mar. 31, 2020 | Mar. 31, 2021 USD ($) security | Dec. 31, 2020 USD ($) security
Investment Holdings [Line Items] |  |  |  |
Vertical risk retention interest | 5.00% | 5.00% | 5.00% |
Trading investments |  |  | $ 30,594 | $ 16,923
Number of mortgage-backed securities with unrealized losses | security |  |  | 40 | 14
Number of mortgage-backed securities | security |  |  | 175 | 163
Available-for-sale investments, cost |  |  | $ 2,116,279 | $ 1,986,957
Par value of mortgage-backed securities pledged to FRB |  |  | 786,000 | 815,000
Non-marketable securities investment |  |  | 26,000 | 26,000
Low income housing tax credit investments |  |  | 52,000 | 54,000
Low income housing tax credit investments, liability for unfunded commitments |  |  | 15,000 | 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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