Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Class of Stock [Line Items]
Noncontrolling interest reclassified to equity	$ 0	$ 0
Common stock dividends and operating partnership unit distributions	14,749
Convertible Common Stock
Class of Stock [Line Items]
Units converted to common stock	9,825	131,844
Noncontrolling interest reclassified to equity	95	1,279
Common Stock and Operating Partnership Units
Class of Stock [Line Items]
Common stock dividends and operating partnership unit distributions	$ 14,749