Noncontrolling Interest - Holders of Convertible Limited Partnership Units in Operating Partnership - Additional Information (Detail) (Noncontrolling Interest)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Noncontrolling Interest
Noncontrolling Interest [Line Items]
Percentage of ownership interest of noncontrolling interest	25.60%		25.60%
Limited partnership units	7,200,000		7,200,000
Limited partnership units, conversion ratio	1		1
Outstanding stock percent that should be acquired for rights to be exercised	39.90%		39.90%
Limited partnership units convertible in to shares of common stock, eligible for conversion	1,109,000		1,109,000
Fully converted partnership units and diluted weighted average shares outstanding	28,100,000	27,400,000	27,900,000	27,200,000