Consolidated Statements of Changes in Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Capital	Retained Earnings	Treasury Stock	Alexander's Equity	Non-controlling Interest
Balance, at Dec. 31, 2010	$ 343,776	$ 5,173	$ 31,501	$ 304,055	$ (375)	$ 340,354	$ 3,422
Shares Issued, Beginning Balance at Dec. 31, 2010		5,173,000
Net income	60,275			58,789		58,789	1,486
Dividends paid	(45,956)			(45,956)		(45,956)
Distributions	(600)						(600)
Deferred stock unit grant	300		300			300
Balance, at Sep. 30, 2011	357,795	5,173	31,801	316,888	(375)	353,487	4,308
Shares Issued, Ending Balance at Sep. 30, 2011		5,173,000
Balance, at Dec. 31, 2011	363,245	5,173	31,801	322,201	(375)	358,800	4,445
Shares Issued, Beginning Balance at Dec. 31, 2011	5,173,450	5,173,000
Net income	58,010			57,230		57,230	780
Dividends paid	(57,458)			(57,458)		(57,458)
Deferred stock unit grant	300		300			300
Balance, at Sep. 30, 2012	$ 364,097	$ 5,173	$ 32,101	$ 321,973	$ (375)	$ 358,872	$ 5,225
Shares Issued, Ending Balance at Sep. 30, 2012	5,173,450	5,173,000