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, 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	40,490	13	40,477
Common stock redemptions	(798)		(798)
Share-based compensation	7,449	1	7,448
Net income	88,058				88,058
Reclassification adjustments for losses included in net income (interest expense)	2,367			2,367
Gains (losses) arising during the period on interest rate swaps	(15,459)			(15,459)
Dividends to common stockholders (in usd per share)	(121,741)					(121,741)
Ending balance at Sep. 30, 2020	1,900,375	1,361	3,532,130	(19,267)	1,215,362	(2,829,211)
Beginning balance at Jun. 30, 2020	1,929,361	1,360	3,529,559	(20,294)	1,207,132	(2,788,396)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	127	1	126
Share-based compensation	2,445		2,445
Net income	8,230				8,230
Reclassification adjustments for losses included in net income (interest expense)	1,101			1,101
Gains (losses) arising during the period on interest rate swaps	(74)			(74)
Dividends to common stockholders (in usd per share)	(40,815)					(40,815)
Ending balance at Sep. 30, 2020	1,900,375	1,361	3,532,130	(19,267)	1,215,362	(2,829,211)
Beginning balance at Dec. 31, 2020	1,948,376	1,395	3,635,341	(17,832)	1,199,499	(2,870,027)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	240,738	78	240,660
Common stock redemptions	(1,610)		(1,610)
Share-based compensation	8,183	2	8,181
Net income	45,052				45,052
Reclassification adjustments for losses included in net income (interest expense)	3,340			3,340
Gains (losses) arising during the period on interest rate swaps	2,079			2,079
Dividends to common stockholders (in usd per share)	(130,825)					(130,825)
Ending balance at Sep. 30, 2021	2,115,333	1,475	3,882,572	(12,413)	1,244,551	(3,000,852)
Beginning balance at Jun. 30, 2021	2,096,254	1,455	3,818,592	(13,580)	1,246,617	(2,956,830)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	61,462	20	61,442
Share-based compensation	2,538		2,538
Net income	(2,066)				(2,066)
Reclassification adjustments for losses included in net income (interest expense)	1,131			1,131
Gains (losses) arising during the period on interest rate swaps	36			36
Dividends to common stockholders (in usd per share)	(44,022)					(44,022)
Ending balance at Sep. 30, 2021	$ 2,115,333	$ 1,475	$ 3,882,572	$ (12,413)	$ 1,244,551	$ (3,000,852)