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	40,363	12	40,351
Common stock redemptions	(798)		(798)
Share-based compensation	5,004	1	5,003
Net income	79,828				79,828
Reclassification adjustments for losses included in net income (interest expense)	1,267			1,267
Gains (losses) arising during the period on interest rate swaps and treasury rate locks	(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
Gains (losses) arising during the period on interest rate swaps and treasury rate locks	(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)
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	179,275	59	179,216
Common stock redemptions	(1,611)	(1)	(1,610)
Share-based compensation	5,647	2	5,645
Net income	47,118				47,118
Reclassification adjustments for losses included in net income (interest expense)	2,209			2,209
Gains (losses) arising during the period on interest rate swaps and treasury rate locks	2,043			2,043
Dividends to common stockholders (in usd per share)	(86,803)					(86,803)
Ending balance at Jun. 30, 2021	2,096,254	1,455	3,818,592	(13,580)	1,246,617	(2,956,830)
Beginning balance at Mar. 31, 2021	1,998,109	1,417	3,699,867	(13,887)	1,223,521	(2,912,809)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs	116,191	38	116,153
Common stock redemptions	(55)		(55)
Share-based compensation	2,627	0	2,627
Net income	23,096				23,096
Reclassification adjustments for losses included in net income (interest expense)	1,114			1,114
Gains (losses) arising during the period on interest rate swaps and treasury rate locks	(807)			(807)
Dividends to common stockholders (in usd per share)	(44,021)					(44,021)
Ending balance at Jun. 30, 2021	$ 2,096,254	$ 1,455	$ 3,818,592	$ (13,580)	$ 1,246,617	$ (2,956,830)