Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 248,443	$ 302,543
Change in fair value of marketable securities (see Note 5)	$ (11,990)	$ 0	$ 0
Closing share price (in dollars per share)	$ 43.28	$ 65.68
Real estate, net	$ 730,270	$ 754,324
Cash and cash equivalent maturity maximum	3 months
Allowance for doubtful accounts	$ 671	$ 1,501
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings					$ 5,156
Macerich
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in fair value of marketable securities (see Note 5)	$ (11,990)
Closing share price (in dollars per share)	$ 43.28	$ 65.68
Subsequent Event | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Finance lease, right-of-use asset				$ 5,400
Finance lease, liability				$ 5,400
Rego Park I
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of cash mortgage collateralized	100.00%