Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Measurements [Abstract]

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

		As of December 31, 2013
(Amounts in thousands)		Total		Level 1		Level 2		Level 3
	Marketable securities	$	31,522	$	31,522	$	-	$	-
		As of December 31, 2012
(Amounts in thousands)		Total		Level 1		Level 2		Level 3
	Marketable securities	$	31,206	$	31,206	$	-	$	-

Fair Value, by Balance Sheet Grouping [Table Text Block]

			As of December 31, 2013				As of December 31, 2012
			Carrying		Fair		Carrying		Fair
(Amounts in thousands)			Amount		Value		Amount		Value
Assets:
	Cash equivalents	$	184,796	$	184,796	$	289,054	$	289,054
Liabilities:
	Mortgages payable	$	1,049,959	$	1,072,000	$	1,065,916	$	1,097,000
	Leasing commissions (included in Amounts due to Vornado)		42,924		43,000		45,803		46,000
		$	1,092,883	$	1,115,000	$	1,111,719	$	1,143,000