Investment in Real Estate - Net Non-Cash Impairment Charges (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Impairment Charges [Line Items]
Total Net Impairment	$ 1,605	$ 0	$ 1,605	$ 1,101
Held for Sale and Sold Operating Properties - Discontinued Operations
Impairment Charges [Line Items]
Total Net Impairment	176	0	176	1,082
Held for Use Operating Properties - Continuing Operations
Impairment Charges [Line Items]
Total Net Impairment	$ 1,429	$ 0	$ 1,429	$ 19