Consolidated Statement of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid- In-Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Noncontrolling Interests	Series C Preferred Stock Preferred Stock	Series I Preferred Stock Preferred Stock
Beginning Balance at Dec. 31, 2012	$ 6,907,103	$ 913	$ 4,490,084	$ 0	$ (29,587)	$ 1,556,087	$ 487,301	$ 180,340	$ 221,965
Beginning Balance (in shares) at Dec. 31, 2012		91,250
Increase (Decrease) in Stockholders' Equity
Net income	146,000					135,371	10,629
Other comprehensive loss	14,376				14,376
Preferred dividends	(21,881)					(21,881)
DRSPP proceeds	67		67
Conversion of units of the Operating Partnership to common stock (in shares)		239
Conversion of units of the Operating Partnership to common stock	17,287	$ 2	17,285
Redemption of preferred stock	(192,500)					(12,160)		(180,340)
Preferred units issuance costs	(33)								(33)
Reallocation of noncontrolling interest in the Operating Partnership	(45,618)					(45,618)
Deferred compensation plan and stock award, net (in shares)		135
Deferred compensation plan and stock award, net	166	$ 3	4,464	(6,090)		1,789
Amortization of deferred compensation plan	26,329		26,329
Issuance of common stock (in shares)		3,062
Issuance of common stock	290,699	$ 30	290,669
Proceeds from stock options exercised (in shares)		224
Proceeds from stock options exercised	12,904	$ 2	12,902
Sale of treasury stock (in shares)		83
Sale of treasury stock	7,120			6,090		1,030
Contributions to consolidated joint venture interests	8,164						8,164
Cash distributions to noncontrolling interests	(14,623)						(14,623)
Cash distributions declared ($2.52, $2.10, and $1.49 per common share, respectively, none of which represented a return of capital for federal income tax purposes)	(138,684)					(138,684)
Ending Balance at Dec. 31, 2013	7,016,876	$ 950	4,841,800	0	(15,211)	1,475,934	491,471	0	221,932
Ending Balance (in shares) at Dec. 31, 2013		94,993
Increase (Decrease) in Stockholders' Equity
Net income	524,646					518,056	6,590
Other comprehensive loss	8,231				8,231
Preferred dividends	(14,952)					(14,952)
DRSPP proceeds	64		64
Conversion of units of the Operating Partnership to common stock (in shares)		315
Conversion of units of the Operating Partnership to common stock	31,653	$ 3	31,650
Reallocation of noncontrolling interest in the Operating Partnership	(168,439)					(168,439)
Deferred compensation plan and stock award, net (in shares)		15
Deferred compensation plan and stock award, net	(1,514)		(15)			(1,499)
Amortization of deferred compensation plan	29,749		29,749
Issuance of common stock (in shares)		1,654
Issuance of common stock	185,321	$ 17	185,304
Proceeds from stock options exercised (in shares)		348
Proceeds from stock options exercised	25,211	$ 4	25,207
Contributions to consolidated joint venture interests	30,800						30,800
Cash distributions to noncontrolling interests	(7,019)						(7,019)
Cash distributions declared ($2.52, $2.10, and $1.49 per common share, respectively, none of which represented a return of capital for federal income tax purposes)	(201,411)					(201,411)
Ending Balance at Dec. 31, 2014	7,459,216	$ 974	5,113,759	0	(6,980)	1,607,689	521,842	0	221,932
Ending Balance (in shares) at Dec. 31, 2014		97,325
Increase (Decrease) in Stockholders' Equity
Net income	299,927					284,084	15,843
Acquisition of subsidiary interest from noncontrolling interest	(20,650)		(9,566)				(11,084)
Other comprehensive loss	(1,769)				(1,769)
Preferred dividends	(14,952)					(14,952)
DRSPP (in shares)		776
DRSPP proceeds	99,555	$ 8	99,547
Conversion of units of the Operating Partnership to common stock (in shares)		483
Conversion of units of the Operating Partnership to common stock	55,697	$ 5	55,692
Reallocation of noncontrolling interest in the Operating Partnership	20,915					20,915
Reallocation of capital account relating to sale	(10,143)						(10,143)
Deferred compensation plan and stock award, net (in shares)		168
Deferred compensation plan and stock award, net	(2,982)	$ 2	243			(3,227)
Amortization of deferred compensation plan	26,721		26,721
Issuance of common stock (in shares)		1,007
Issuance of common stock	126,989	$ 10	136,979	(10,000)
Proceeds from stock options exercised (in shares)		217
Proceeds from stock options exercised	16,362	$ 2	16,360
Contributions to consolidated joint venture interests	35,178						35,178
Cash distributions to noncontrolling interests	(119,784)						(119,784)
Cash distributions declared ($2.52, $2.10, and $1.49 per common share, respectively, none of which represented a return of capital for federal income tax purposes)	(250,963)					(250,963)
Ending Balance at Dec. 31, 2015	$ 7,719,317	$ 1,001	$ 5,439,735	$ (10,000)	$ (8,749)	$ 1,643,546	$ 431,852	$ 0	$ 221,932
Ending Balance (in shares) at Dec. 31, 2015		99,976