Marketable Securities (Details) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Investment Holdings [Line Items]
Fair Value	$ 34,166	$ 31,522
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	$ 34,166	$ 31,522
Closing share price (in dollars per share)	$ 63.83	$ 58.89