CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Shares	Common Shares	Additional Paid-in Capital	Accumulated Distributions in Excess of Net Income	Deferred Compensation Obligation	Accumulated Other Comprehensive Loss	Treasury Stock at Cost	Non-Controlling Interests
Balance at Dec. 31, 2013	$ 3,927,879	$ 405,000	$ 35,938	$ 5,417,363	$ (1,915,638)	$ 16,702	$ (36,493)	$ (18,211)	$ 23,218
Balance, shares at Dec. 31, 2013			359,379
Issuance of common shares related to stock plans	6,930	0	$ 40	6,066	0	0	0	824	0
Issuance of common shares related to stock plans, shares			397
Issuance of common shares for cash offering	11,634	0	$ 66	11,568	0	0	0	0	0
Issuance of common shares for cash offering, shares			664
Stock-based compensation, net	2,539	0	$ 27	1,864	0	(93)	0	741	0
Stock-based compensation, net, shares			271
Issuance of OP Units	18,256	0	$ 0	0	0	0	0	0	18,256
Contributions from non-controlling interests	93	0	0	0	0	0	0	0	93
Distributions to non-controlling interests	(14,184)	0	0	0	0	0	0	0	(14,184)
Redemption of preferred shares	(55,026)	(55,000)	0	1,917	(1,943)	0	0	0	0
Dividends declared-common shares	(223,016)	0	0	0	(223,016)	0	0	0	0
Dividends declared-preferred shares	(23,897)	0	0	0	(23,897)	0	0	0	0
Comprehensive income (loss)	146,320	0	0	0	117,282	0	29,141	0	(103)
Balance at Dec. 31, 2014	3,797,528	350,000	$ 36,071	5,438,778	(2,047,212)	16,609	(7,352)	(16,646)	27,280
Balance, shares at Dec. 31, 2014			360,711
Issuance of common shares related to stock plans	7,388	0	$ 44	7,214	0	0	0	130	0
Issuance of common shares related to stock plans, shares			435
Stock-based compensation, net	2,979	0	$ 6	4,123	0	(1,072)	0	(78)	0
Stock-based compensation, net, shares			60
Issuance of common stock in settlement of conversion feature (Note 7)	(144)	0	$ 304	(1,726)	0	0	0	1,278	0
Issuance of common stock in settlement of conversion feature (Note 7), shares			3,043
Redemption of OP Units	(30)	0	$ 104	18,122	0	0	0	0	(18,256)
Redemption of OP Units, shares			1,043
Distributions to non-controlling interests	(1,817)	0	$ 0	0	0	0	0	0	(1,817)
Dividends declared-common shares	(250,038)	0	0	0	(250,038)	0	0	0	0
Dividends declared-preferred shares	(22,375)	0	0	0	(22,375)	0	0	0	0
Comprehensive income (loss)	(70,022)	0	0	0	(72,168)	0	1,069	0	1,077
Balance at Dec. 31, 2015	3,463,469	350,000	$ 36,529	5,466,511	(2,391,793)	15,537	(6,283)	(15,316)	8,284
Balance, shares at Dec. 31, 2015			365,292
Issuance of common shares related to stock plans	16,440	0	$ 101	14,747	0	0	0	1,592	0
Issuance of common shares related to stock plans, shares			1,006
Stock-based compensation, net	4,333	0	$ 0	5,954	0	(388)	0	(1,233)	0
Stock-based compensation, net, shares			0
Distributions to non-controlling interests	(1,093)	0	$ 0	0	0	0	0	0	(1,093)
Dividends declared-common shares	(278,171)	0	0	0	(278,171)	0	0	0	0
Dividends declared-preferred shares	(22,375)	0	0	0	(22,375)	0	0	0	0
Comprehensive income (loss)	63,409	0	0	0	60,012	0	2,091	0	1,306
Balance at Dec. 31, 2016	$ 3,246,012	$ 350,000	$ 36,630	$ 5,487,212	$ (2,632,327)	$ 15,149	$ (4,192)	$ (14,957)	$ 8,497
Balance, shares at Dec. 31, 2016			366,298