Indebtedness (Debt issuances and retirements) - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Debt Instrument [Line Items]
Net gain (loss) on extinguishment of indebtedness		$ 0	$ (4,287)	$ (197)	$ (4,287)
Secured Mortgage Notes [Member] | Dallas, Texas [Member]
Debt Instrument [Line Items]
Prepaid secured mortgage indebtedness	$ 120,000
Net gain (loss) on extinguishment of indebtedness			$ (4,287)		$ (4,287)