UNAUDITED SUMMARIZED CONSOLIDATED QUARTERLY FINANCIAL DATA (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly financial data
Rental income	$ 302,745	$ 289,008	$ 278,463	$ 267,922	$ 264,732	$ 263,256	$ 256,634	$ 250,483	$ 1,138,138	$ 1,035,105	$ 984,309
Income/(loss) from continuing operations									199,579	221,542	132,655
Net income/(loss)	105,237	29,422	38,318	26,602	$ 89,615	$ 20,258	$ 22,444	$ 89,225	$ 199,579	$ 221,542	$ 132,655
Net income/(loss) attributable to common stockholders	$ 96,928	$ 26,173	$ 34,588	$ 23,492
Income/(loss) per weighted average common share - basic	$ 0.33	$ 0.09	$ 0.12	$ 0.08	$ 0.30	$ 0.07	$ 0.07	$ 0.30	$ 0.63	$ 0.74	$ 0.44
Income/(loss) per weighted average common share - diluted	$ 0.33	$ 0.09	$ 0.12	$ 0.08	$ 0.30	$ 0.07	$ 0.07	$ 0.30	$ 0.63	$ 0.74	$ 0.44
Weighted average number of common shares outstanding - Basic	293,107	288,706	281,960	277,002	270,107	267,727	267,311	267,546	285,247	268,179	267,024
Weighted average number of common shares outstanding - diluted	294,073	289,529	282,575	277,557	270,755	268,861	268,890	269,208	286,015	269,483	268,830