Other Assets (Details Textual) (USD $) In Thousands, unless otherwise specified			6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 One Beach Street [Member]
Other Assets (Textual) [Abstract]
Net of accumulated amortization of leasing commissions	$ 16,002	$ 14,722
Net of accumulated amortization of lease incentives	2,035	1,850
Net of accumulated amortization of other intangible assets	4,134	3,885
Net of accumulated amortization of debt issuance costs	$ 2,220	$ 2,509
Acquisition completion date			Jan. 24, 2012