Consolidated Statement 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
Total equity at Dec. 31, 2009	$ 314,626	$ 5,173	$ 31,501	$ 275,921	$ (375)	$ 312,220	$ 2,406
Shares Issued, Beginning Balance at Dec. 31, 2009		5,173,000
Net income	49,572			48,538		48,538	1,034
Dividends paid	(25,530)			(25,530)		(25,530)
Total equity at Sep. 30, 2010	338,668	5,173	31,501	298,929	(375)	335,228	3,440
Shares Issued, Ending Balance at Sep. 30, 2010		5,173,000
Total equity 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	5,173,450	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
Total equity 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	5,173,450	5,173,000