Condensed Consolidated Statements of Equity (Unaudited) Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Cumulative Net Income	Cumulative Dividends
Beginning balance at Dec. 31, 2018	$ 1,716,642	$ 1,253	$ 3,180,284	$ (902)	$ 1,088,119	$ (2,552,112)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	120,500	38	120,462
Common stock redemptions	(570)		(570)
Share-based compensation	2,639	1	2,638
Net income	4,891				4,891
Reclassification adjustments for losses included in net income (interest expense)	15			15
Losses arising during the period on interest rate swaps	(724)			(724)
Dividends to common stockholders	(37,614)					(37,614)
Ending balance at Mar. 31, 2019	1,805,779	1,292	3,302,814	(1,611)	1,093,010	(2,589,726)
Beginning balance at Dec. 31, 2019	1,900,009	1,347	3,485,003	(6,175)	1,127,304	(2,707,470)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	7,321	2	7,319
Common stock redemptions	(798)		(798)
Share-based compensation	2,599		2,599
Net income	4,315				4,315
Reclassification adjustments for losses included in net income (interest expense)	328			328
Losses arising during the period on interest rate swaps	(13,930)			(13,930)
Dividends to common stockholders	(40,416)					(40,416)
Ending balance at Mar. 31, 2020	$ 1,859,428	$ 1,349	$ 3,494,123	$ (19,777)	$ 1,131,619	$ (2,747,886)