Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
REVENUES
Property rentals	$ 174,634	$ 166,403	$ 155,275
Expense reimbursements	79,618	74,947	68,254
Total revenues	254,252	241,350	223,529
EXPENSES
Operating (including fees to Vornado of $5,488, $5,182, and $4,948, respectively)	84,936	78,652	73,340
Depreciation and amortization	34,031	31,343	27,284
General and administrative (including a reversal of stock appreciation rights ("SARs") expense of $34,275 in 2009, and management fees to Vornado of $2,160 in each year)	4,357	7,792	(28,246)
Total expenses	123,324	117,787	72,378
OPERATING INCOME	130,928	123,563	151,151
Interest and other income, net	2,672	851	2,847
Interest and debt expense	(52,659)	(58,372)	(57,473)
Net loss on early extinguishment of debt	0	(1,238)	(519)
Income before income taxes	80,941	64,804	96,006
Income tax benefit	105	2,641	36,935
Net income	81,046	67,445	132,941
Net income attributable to the noncontrolling interest	(1,623)	(1,016)	(751)
Net income attributable to Alexander's	$ 79,423	$ 66,429	$ 132,190
Net income per common share - basic
Net income per common share - basic	$ 15.55	$ 13.01	$ 25.90
Weighted average shares - basic	5,106,568	5,105,936	5,103,790
Net income per common share - diluted
Net income per common share - diluted	$ 15.55	$ 13.01	$ 25.89
Weighted average shares - diluted	5,106,568	5,105,936	5,105,370
Dividends per common share	$ 12.00	$ 7.50	$ 0