CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Accumulated Distributions in Excess of Earnings	Accumulated Other Comprehensive Loss
Balance, (shares) at Dec. 31, 2018		311,381,396
Balance at Dec. 31, 2018	$ 1,816,850	$ 3,114	$ 2,607,330	$ (804,617)	$ 11,023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (shares)		2,267,609
Issuance of common stock	21,247	$ 22	21,225
Equity-based compensation	32		32
Distributions declared on common stock	(47,963)			(47,963)
Redemptions of common stock (shares)		(2,318,505)
Redemptions of common stock	(21,724)	$ (23)	(21,701)
Changes in redeemable common stock	(67)		(67)
Comprehensive income (loss)	3,496			8,817	(5,321)
Balance, (shares) at Mar. 31, 2019		311,330,500
Balance at Mar. 31, 2019	1,771,871	$ 3,113	2,606,819	(843,763)	5,702
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting changes	$ (2,002)			(2,002)
Balance, (shares) at Dec. 31, 2019	311,207,725	311,207,725.099
Balance at Dec. 31, 2019	$ 1,789,948	$ 3,112	2,606,925	(816,181)	(3,908)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (shares)		2,223,298
Issuance of common stock	19,231	$ 22	19,209
Equity-based compensation	40		40
Distributions declared on common stock	(48,332)			(48,332)
Redemptions of common stock (shares)		(2,256,037)
Redemptions of common stock	(19,514)	$ (22)	(19,492)
Changes in redeemable common stock	283		283
Comprehensive income (loss)	$ (22,003)			(12,175)	(9,828)
Balance, (shares) at Mar. 31, 2020	311,174,986	311,174,986.099
Balance at Mar. 31, 2020	$ 1,717,651	$ 3,112	$ 2,606,965	$ (878,690)	$ (13,736)