Commitments and Contingencies - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013
Property, Plant and Equipment [Line Items]
Expire date of ground lease	Jun. 01, 2053
CBS [Member]
Property, Plant and Equipment [Line Items]
Percentage of net proceeds	50.00%
Payable amount of sale of property	$ 134,000
Additional contingent fee	340,000
Minimum [Member] | CBS [Member]
Property, Plant and Equipment [Line Items]
Amount in excess of net of closing cost	6,500,000
Ground Lease [Member]
Property, Plant and Equipment [Line Items]
Future funding commitments	42,815,000
Ground Lease Commitments, 2013	657,000
Ground Lease Commitments, 2014	1,405,000
Ground Lease Commitments, 2015	1,463,000
Ground Lease Commitments, 2016	1,592,000
Ground Lease Commitments, 2017	1,656,000
Ground Lease Commitments, Thereafter	$ 109,419,000