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Marketable Securities (Details) - USD ($) $ / shares in Units, $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Marketable Securities [Line Items] |  |
Marketable securities | $ 6,024 | $ 14,409
Common Stock |  |
Marketable Securities [Line Items] |  |
Investment owned, balance, shares | 564,612 | 535,265
Macerich |  |
Marketable Securities [Line Items] |  |
Closing share price (in dollars per share) | $ 10.67 | $ 26.92

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