Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
REVENUES
Property rentals	$ 134,847	$ 133,682	$ 127,240
Expense reimbursements	56,465	51,564	46,966
Total revenues	191,312	185,246	174,206
EXPENSES
Operating, including fees to Vornado of $4,318, $3,687, and $3,665, respectively	61,755	55,481	50,153
Depreciation and amortization	28,815	28,083	25,688
General and administrative, including management fees to Vornado of $2,160 in each year	5,162	3,996	7,374
Total expenses	95,732	87,560	83,215
OPERATING INCOME	95,580	97,686	90,991
Interest and other income, net	177	1,001	799
Interest and debt expense	(45,652)	(43,898)	(45,455)
Income before income taxes	50,105	54,789	46,335
Income tax (expense) benefit	(64)	42	2,824
Income from continuing operations	50,041	54,831	49,159
Income from discontinued operations, including a $599,628 net gain on sale of real estate in 2012	624,952	26,215	18,286
Net income	674,993	81,046	67,445
Net income attributable to the noncontrolling interest	(606)	(1,623)	(1,016)
Net income attributable to Alexander's	$ 674,387	$ 79,423	$ 66,429
Income per common share- basic and diluted
Income from continuing operations- basic and diluted (in dollars per share)	$ 9.80	$ 10.74	$ 9.63
Income from discontinued operations, net - basic and diluted (in dollars per share)	$ 122.24	$ 4.81	$ 3.38
Net income per common share (in dollars per share)	$ 132.04	$ 15.55	$ 13.01
Weighted average shares outstanding - basic and diluted (in shares)	5,107,610	5,106,568	5,105,936