Investment in Real Estate - Net Non-Cash Impairment Charges (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Impairment Charges [Line Items]
Total Net Impairment	$ 1,047	$ 0	$ 2,652	$ 1,246
Held for Sale and Sold Operating Properties - Discontinued Operations
Impairment Charges [Line Items]
Total Net Impairment	0	0	176	1,503
Operating Properties Marketed For Sale - Continuing Operations
Impairment Charges [Line Items]
Total Net Impairment	$ 1,047	$ 0	$ 2,476	$ (257)