Marketable Securities - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Economic basis per share (in usd per share)	$ 56.05
Economic cost	$ 30,000
Fair value	$ 16,909	$ 23,166
Common Stock
Investment Holdings [Line Items]
Macerich common shares (shares)	535,265	535,265
Macerich
Investment Holdings [Line Items]
Closing share price (in usd per share)	$ 31.59	$ 43.28

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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).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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Balance held at close of period in number of shares.

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- Definition

Amount of investment in marketable security.

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Price of a single share of a number of saleable stocks of a company.

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