Earnings Per Common Share - Schedule of Computation of Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Line Items]
Net income attributable to common stockholders	$ 82,282	$ 82,592
Earnings and dividends allocated to participating securities	(197)	(165)
Earnings for basic computations	82,085	82,427
Income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) and Operating Partnership	4,049	5,474
Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units)	(1,271)	(1,271)
Net income for diluted computations	$ 84,863	$ 86,630
Weighted average common shares outstanding:
Average number of common shares outstanding - basic (in shares)	125,605,403	124,754,174
OP Units (in shares)	5,596,191	5,621,470
Shares related to exchangeable senior notes and dilutive stock options (in shares)	541,570	704,970
Average number of common shares outstanding - diluted (in shares)	132,618,644	131,956,094
Earnings per common share
Basic (in dollars per share)	$ 0.65	$ 0.66
Diluted (in dollars per share)	$ 0.64	$ 0.66
Series A Units [Member]
Weighted average common shares outstanding:
Preferred series units (in shares)	875,480	875,480