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Marketable Securities (Details) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Oct. 31, 2015 USD ($) | Dec. 31, 2015 USD ($) specialdividends $ / shares shares | Dec. 31, 2015 USD ($) specialdividends $ / shares shares | Dec. 31, 2014 USD ($) $ / shares shares
Investment Holdings [Line Items] |  |  |  |
Fair Value |  | $ 43,191 | $ 43,191 | $ 44,646
Macerich interest [Member] |  |  |  |
Investment Holdings [Line Items] |  |  |  |
Macerich Common Shares | shares |  | 535,265 | 535,265 | 535,265
Economic basis per share (in dollars per share) | $ / shares |  | $ 56.05 | $ 56.05 |
GAAP Cost |  | $ 30,000 | $ 30,000 |
Fair Value |  | $ 43,191 | $ 43,191 | $ 44,646
Closing share price (in dollars per share) | $ / shares |  | $ 80.69 | $ 80.69 | $ 83.41
Unrealized gain (loss) |  |  | $ (1,455) | $ 13,124
Number Of Special Dividends | specialdividends |  | 2 | 2 |
Special Dividends Per Share | $ / shares |  | $ 2 |  |
Investment Income Dividend | $ 2,141 |  |  |

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