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
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 (loss)	38,007			38,364		38,364	(357)
Dividends paid	(30,636)			(30,636)		(30,636)
Distributions	(600)						(600)
Deferred stock unit grant	300		300			300
Balance, at Jun. 30, 2011	350,847	5,173	31,801	311,783	(375)	348,382	2,465
Shares Issued, Ending Balance at Jun. 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 (loss)	38,662			38,374		38,374	288
Dividends paid	(38,303)			(38,303)		(38,303)
Deferred stock unit grant	300		300			300
Balance, at Jun. 30, 2012	$ 363,904	$ 5,173	$ 32,101	$ 322,272	$ (375)	$ 359,171	$ 4,733
Shares Issued, Ending Balance at Jun. 30, 2012	5,173,450	5,173,000