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]	Treasury Stock at Cost [Member]	Non-Controlling Interests [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Beginning Balance at Dec. 31, 2020	$ 1,944,823	$ 325,000	$ 19,400	$ 5,705,164	$ (4,099,534)	$ 5,479	$ (11,319)	$ 3,315	$ (2,682)
Issuance of common shares related to stock plans	37	0	6	31	0	0	0	0	0
Issuance of common shares for cash offering	225,529	0	1,696	219,910	0	0	3,923	0	0
Stock-based compensation, net	10,621	0	0	8,580	0	(968)	3,009	0	0
Distributions to non-controlling interests	(16)	0	0	0	0	0	0	(16)	0
Dividends declared-common shares	(23,303)	0	0	0	(23,303)	0	0	0	0
Dividends declared-preferred shares	(4,950)	0	0	0	(4,950)	0	0	0	0
Comprehensive income	18,863	0	0	0	16,008	0	0	173	2,682
Ending Balance at Mar. 31, 2021	2,171,604	325,000	21,102	5,933,685	(4,111,779)	4,511	(4,387)	3,472	$ 0
Beginning Balance at Dec. 31, 2021	2,042,652	175,000	21,129	5,934,166	(4,092,783)	4,695	(5,349)	5,794
Issuance of common shares related to stock plans	69	0	65	4	0	0	0	0
Issuance of common shares for cash offering	33,781	0	223	33,558	0	0	0	0
Stock-based compensation, net	(3,627)	0	0	996	0	(24)	(4,599)	0
Distributions to non-controlling interests	(18)	0	0	0	0	0	0	(18)
Dividends declared-common shares	(27,905)	0	0	0	(27,905)	0	0	0
Dividends declared-preferred shares	(2,789)	0	0	0	(2,789)	0	0	0
Comprehensive income	13,955	0	0	0	13,937	0	0	18
Ending Balance at Mar. 31, 2022	$ 2,056,118	$ 175,000	$ 21,417	$ 5,968,724	$ (4,109,540)	$ 4,671	$ (9,948)	$ 5,794