Earnings Per Common Share - Schedule of Computation of Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Class of Stock [Line Items]
Net income attributable to common stockholders	$ 130,418	$ 93,764	$ 313,827	$ 263,052
Earnings and dividends allocated to participating securities	(219)	(191)	(550)	(595)
Earnings for basic computations	130,199	93,573	313,277	262,457
Earnings and dividends allocated to participating securities	0	191	550	595
Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units	7,336	5,163	17,191	15,448
Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units)	(572)	(572)	(1,716)	(2,547)
Net income for diluted computations	$ 136,963	$ 98,355	$ 329,302	$ 275,953
Weighted average common shares outstanding:
Average number of common shares outstanding - basic (in shares)	126,466,837	125,717,517	125,959,926	125,665,787
OP Units (in shares)	5,636,845	5,590,231	5,650,599	5,586,908
Unvested restricted stock awards included for treasury stock method (in shares)	0	280,484	250,630	288,831
Shares related to exchangeable senior notes and dilutive stock options (in shares)	269,390	580,761	279,055	591,616
Average number of common shares outstanding - diluted (in shares)	134,240,290	133,044,473	133,015,690	133,008,622
Earnings per common share
Basic (in dollars per share)	$ 1.03	$ 0.74	$ 2.49	$ 2.09
Diluted (in dollars per share)	$ 1.02	$ 0.74	$ 2.48	$ 2.07
Series A Units
Weighted average common shares outstanding:
Preferred series units (in shares)	875,480	875,480	875,480	875,480
Series D Units
Weighted average common shares outstanding:
Preferred series units (in shares)	991,738	0	0	0