Significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2012

Accounting Policies [Abstract]

Reconciliation Of Net Income Attributable To Common Stockholders To Estimated Taxable Income [Table Text Block]

(Unaudited and in thousands)		Years Ended December 31,
		2012		2011		2010
Net income attributable to Alexander’s		$	674,387	$	79,423	$	66,429
Additional tax gain on sale of the Kings Plaza Regional
	Shopping Center		23,928		-		-
Straight-line rent adjustments			(4,475)		(12,609)		(15,182)
Depreciation and amortization timing differences			910		1,263		602
Interest expense			29		(2,425)		-
Reversal of liability for income taxes			-		-		(3,162)
Other			4,396		(3,429)		6,245
Taxable income before net operating loss ("NOL")			699,175		62,223		54,932
NOL carried forward			-		-		(16,939)
Estimated taxable income		$	699,175	$	62,223	$	37,993