Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Class of Stock [Line Items]
Noncontrolling interest reclassified to equity	$ 0	$ 0
Common stock dividends and operating partnership unit distributions	$ 29,481
Convertible Common Stock
Class of Stock [Line Items]
Units converted to common stock	10,395	137,463
Noncontrolling interest reclassified to equity	$ 100	$ 1,333
Common Stock and Operating Partnership Units
Class of Stock [Line Items]
Common stock dividends and operating partnership unit distributions	$ 29,481