Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

		As of December 31, 2012
(Amounts in thousands)		Total		Level 1		Level 2		Level 3
	Marketable securities	$	31,206	$	31,206	$	-	$	-

			As of December 31, 2012				As of December 31, 2011
			Carrying		Fair		Carrying		Fair
(Amounts in thousands)			Amount		Value		Amount		Value
Assets:
	Cash equivalents	$	289,054	$	289,054	$	35,000	$	35,000
	Short-term investments		-		-		5,000		5,000
		$	289,054	$	289,054	$	40,000	$	40,000
Liabilities:
	Mortgages payable	$	1,065,916	$	1,097,000	$	1,080,932	$	1,102,000
	Leasing commissions (included in Amounts due to Vornado)		45,803		46,000		40,728		41,000
		$	1,111,719	$	1,143,000	$	1,121,660	$	1,143,000