CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Preferred Shares [Member]	Common Shares [Member]	Additional Paid-in Capital [Member]	Accumulated Distributions in Excess of Net Income [Member]	Deferred Compensation Obligation [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock at Cost [Member]	Non-Controlling Interests [Member]
Beginning Balance at Dec. 31, 2019	$ 1,981,478	$ 325,000	$ 19,382	$ 5,700,400	$ (4,066,099)	$ 7,929	$ (491)	$ (7,707)	$ 3,064
Issuance of common shares related to stock plans	(60)	0	18	(78)	0	0	0	0	0
Repurchase of common shares	(7,500)	0	0	0	0	0	0	(7,500)	0
Stock-based compensation, net	4,440	0	0	4,397	0	(2,495)	0	2,538	0
Distributions to non-controlling interests	(278)	0	0	0	0	0	0	0	(278)
Dividends declared-common shares	(38,914)	0	0	0	(38,914)	0	0	0	0
Dividends declared-preferred shares	(10,266)	0	0	0	(10,266)	0	0	0	0
Comprehensive (loss) income	30,904	0	0	0	29,720	0	679	0	505
Ending Balance at Jun. 30, 2020	1,959,804	325,000	19,400	5,704,719	(4,085,559)	5,434	188	(12,669)	3,291
Beginning Balance at Dec. 31, 2019	1,981,478	325,000	19,382	5,700,400	(4,066,099)	7,929	(491)	(7,707)	3,064
Comprehensive (loss) income	34,391
Ending Balance at Sep. 30, 2020	1,959,712	325,000	19,400	5,706,225	(4,083,405)	5,442	(3,728)	(12,463)	3,241
Beginning Balance at Jun. 30, 2020	1,959,804	325,000	19,400	5,704,719	(4,085,559)	5,434	188	(12,669)	3,291
Stock-based compensation, net	1,720	0	0	1,506	0	8	0	206	0
Distributions to non-controlling interests	(166)	0	0	0	0	0	0	0	(166)
Dividends declared-preferred shares	(5,133)	0	0	0	(5,133)	0	0	0	0
Comprehensive (loss) income	3,487	0	0	0	7,287	0	(3,916)	0	116
Ending Balance at Sep. 30, 2020	1,959,712	325,000	19,400	5,706,225	(4,083,405)	5,442	(3,728)	(12,463)	3,241
Beginning Balance at Dec. 31, 2020	1,944,823	325,000	19,400	5,705,164	(4,099,534)	5,479	(2,682)	(11,319)	3,315
Issuance of common shares related to stock plans	99	0	8	91	0	0	0	0	0
Issuance of common shares for cash offering	225,330	0	1,696	219,711	0	0	0	3,923	0
Stock-based compensation, net	12,515	0	0	10,425	0	(995)	0	3,085	0
Distributions to non-controlling interests	(33)	0	0	0	0	0	0	0	(33)
Redemption of preferred shares	(150,019)	(150,000)	0	5,137	(5,156)	0	0	0	0
Dividends declared-common shares	(48,795)	0	0	0	(48,795)	0	0	0	0
Dividends declared-preferred shares	(7,739)	0	0	0	(7,739)	0	0	0	0
Comprehensive (loss) income	40,850	0	0	0	37,877	0	2,682	0	291
Ending Balance at Jun. 30, 2021	2,017,031	175,000	21,104	5,940,528	(4,123,347)	4,484	0	(4,311)	3,573
Beginning Balance at Dec. 31, 2020	1,944,823	325,000	19,400	5,705,164	(4,099,534)	5,479	(2,682)	(11,319)	3,315
Comprehensive (loss) income	69,007
Ending Balance at Sep. 30, 2021	2,018,467	175,000	21,110	5,942,466	(4,123,534)	4,590	0	(4,815)	3,650
Beginning Balance at Jun. 30, 2021	2,017,031	175,000	21,104	5,940,528	(4,123,347)	4,484	0	(4,311)	3,573
Issuance of common shares related to stock plans	133	0	6	127	0	0	0	0	0
Issuance of common shares for cash offering	(164)	0	0	(164)	0	0	0	0	0
Stock-based compensation, net	1,577	0	0	1,975	0	106	0	(504)	0
Distributions to non-controlling interests	(16)	0	0	0	0	0	0	0	(16)
Dividends declared-common shares	(25,462)	0	0	0	(25,462)	0	0	0	0
Dividends declared-preferred shares	(2,789)	0	0	0	(2,789)	0	0	0	0
Comprehensive (loss) income	28,157	0	0	0	28,064	0	0	0	93
Ending Balance at Sep. 30, 2021	$ 2,018,467	$ 175,000	$ 21,110	$ 5,942,466	$ (4,123,534)	$ 4,590	$ 0	$ (4,815)	$ 3,650