Company Earnings Per Share - Schedule of Computation of Basic and Diluted Net Income Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income from continuing operations	$ 47,991	$ 27,171	$ 62,244	$ 47,128
Noncontrolling interests - consolidated real estate entities	(154)	(58)	(138)	(55)
Noncontrolling interests - Operating Partnership	(118)	(68)	(151)	(120)
Distributions to preferred	(922)	(922)	(1,844)	(1,844)
Unvested restricted stock (allocation of earnings)	(110)	(60)	(132)	(97)
Income from continuing operations available to common shareholders	46,687	26,064	59,979	45,014
Weighted average shares outstanding - basic	54,223	54,464	54,199	54,450
Dilutive shares from stock options	112	194	115	198
Weighted average shares outstanding - diluted	54,335	54,658	54,314	54,648
Basic	$ 0.86	$ 0.48	$ 1.11	$ 0.83
Diluted	$ 0.86	$ 0.48	$ 1.10	$ 0.82
Continuing Operations [Member]
Noncontrolling interests - Operating Partnership		$ (67)		$ (118)