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	120,658	38	120,620
Common stock redemptions	(570)		(570)
Share-based compensation	5,011	1	5,010
Net income	9,375				9,375
Reclassification adjustments for losses included in net income (interest expense)	15
Reclassification adjustments for losses included in net income (interest expense)				14
Losses arising during the period on interest rate swaps	(5,301)			(5,301)
Dividends to common stockholders (in usd per share)	(76,385)					(76,385)
Ending balance at Jun. 30, 2019	1,769,444	1,292	3,305,344	(6,189)	1,097,494	(2,628,497)
Beginning balance at Mar. 31, 2019	1,805,779	1,292	3,302,814	(1,611)	1,093,010	(2,589,726)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	159		159
Share-based compensation	2,371		2,371
Net income	4,484				4,484
Reclassification adjustments for losses included in net income (interest expense)	(1)			(1)
Losses arising during the period on interest rate swaps	(4,577)			(4,577)
Dividends to common stockholders (in usd per share)	(38,771)					(38,771)
Ending balance at Jun. 30, 2019	1,769,444	1,292	3,305,344	(6,189)	1,097,494	(2,628,497)
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	40,363	12	40,351
Common stock redemptions	(798)		(798)
Share-based compensation	5,004		5,003
Net income	79,828				79,828
Reclassification adjustments for losses included in net income (interest expense)	1,267			1,267
Losses arising during the period on interest rate swaps	(15,386)			(15,386)
Dividends to common stockholders (in usd per share)	(80,926)					(80,926)
Ending balance at Jun. 30, 2020	1,929,361	1,360	3,529,559	(20,294)	1,207,132	(2,788,396)
Beginning balance at Mar. 31, 2020	1,859,428	1,349	3,494,123	(19,777)	1,131,619	(2,747,886)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	33,042	11	33,031
Share-based compensation	2,405		2,405
Net income	75,513				75,513
Reclassification adjustments for losses included in net income (interest expense)	938			938
Losses arising during the period on interest rate swaps	(1,455)			(1,455)
Dividends to common stockholders (in usd per share)	(40,510)					(40,510)
Ending balance at Jun. 30, 2020	$ 1,929,361	$ 1,360	$ 3,529,559	$ (20,294)	$ 1,207,132	$ (2,788,396)