Marketable Securities (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Fair Value	$ 42,414	$ 43,191
Macerich interest [Member]
Investment Holdings [Line Items]
Macerich Common Shares	535,265	535,265
Economic basis per share (in dollars per share)	$ 56.05
GAAP Cost	$ 30,000
Fair Value	$ 42,414	$ 43,191
Closing share price (in dollars per share)	$ 79.24	$ 80.69