Marketable Securities (Details) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Schedule Of Available For Sale Securities [Line Items]
Change in unrealized net gain on securities available-for-sale	$ 3,254,000	$ 0
Macerich Interest [Member]
Schedule Of Available For Sale Securities [Line Items]
Macerich common shares	535,265
Economic basis per share	$ 56.05
GAAP Cost	30,000,000
Fair Value	34,460,000
Closing share price (in dollars per share)	$ 64.38
Change in unrealized net gain on securities available-for-sale	$ 3,254,000

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

Balance held at close of period in number of shares.

+ References+ Details

- Definition

Net of tax amount of unrealized holding gain (loss) before reclassification adjustments and transfers on available-for-sale securities.

+ References

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+ Details