Summary of Disposition and Each Property's Contribution (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Real Estate Properties [Line Items]
Net income (loss) allocable to common shares	$ (17,844)	$ (7,097)
Disposal Group Held For Sale Or Disposed Of By Sale Not Discontinued Operations
Real Estate Properties [Line Items]
Sale Price	34,699
Gain (loss) on sale	2,199
Net income (loss) allocable to common shares	$ 94
Disposal Group Held For Sale Or Disposed Of By Sale Not Discontinued Operations | Multi family | Ventura
Real Estate Properties [Line Items]
Date of Sale	Mar. 30, 2016
Sale Price	$ 8,750
Gain (loss) on sale	120
Net income (loss) allocable to common shares	$ 37
Disposal Group Held For Sale Or Disposed Of By Sale Not Discontinued Operations | Office | Mineral Or Lincoln
Real Estate Properties [Line Items]
Date of Sale	Mar. 25, 2016
Sale Price	$ 7,949
Gain (loss) on sale	(374)
Net income (loss) allocable to common shares	$ 5
Disposal Group Held For Sale Or Disposed Of By Sale Not Discontinued Operations | IRT | Multi family | Cumberland Glen
Real Estate Properties [Line Items]
Date of Sale	Feb. 18, 2016
Sale Price	$ 18,000
Gain (loss) on sale	2,453
Net income (loss) allocable to common shares	$ 52