Consolidated Statement of Equity - USD ($) $ 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, 2013	$ 7,016,876	$ 950	$ 4,841,800	$ 0	$ (15,211)	$ 1,475,934	$ 491,471	$ 0	$ 221,932
Beginning Balance (in shares) at Dec. 31, 2013		94,993,000
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)		315,000
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)		15,000
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)	1,626,999	1,654,000
Issuance of common stock	$ 185,321	$ 17	185,304
Proceeds from stock options exercised (in shares)		348,000
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		97,325,000
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)		776,000
DRSPP proceeds	99,555	$ 8	99,547
Conversion of units of the Operating Partnership to common stock (in shares)		483,000
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)		168,000
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)		1,007,000
Issuance of common stock	126,989	$ 10	136,979	(10,000)
Proceeds from stock options exercised (in shares)		217,000
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		99,976,000
Increase (Decrease) in Stockholders' Equity
Net income	257,540					249,896	7,644
Other comprehensive loss	30,886				30,886
Preferred dividends	(14,950)					(14,950)
DRSPP (in shares)		2,000
DRSPP proceeds	277		277
Conversion of units of the Operating Partnership to common stock (in shares)		295,000
Conversion of units of the Operating Partnership to common stock	31,806	$ 3	31,803
Reallocation of noncontrolling interest in the Operating Partnership	4,222					4,222
Deferred compensation plan and stock award, net (in shares)		96,000
Deferred compensation plan and stock award, net	(1,988)	$ 1	(1,989)
Amortization of deferred compensation plan	25,890		25,890
Issuance of common stock	(40)	$ 10	113,999	(114,049)
Proceeds from stock options exercised (in shares)		193,000
Proceeds from stock options exercised	14,832	$ 2	14,830
Contributions to consolidated joint venture interests	2,359						2,359
Cash distributions to noncontrolling interests	(15,419)						(15,419)
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)	(295,377)					(295,377)
Ending Balance at Dec. 31, 2016	$ 7,750,911	$ 1,017	$ 5,624,545	$ (124,049)	$ 22,137	$ 1,578,893	$ 426,436	$ 0	$ 221,932
Ending Balance (in shares) at Dec. 31, 2016		100,562,000