Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Cumulative Dividends in excess of Earnings	Accumulated Other Comprehensive Income (Loss)	Total Stockholders' Equity	Noncontrolling Interest - Unit holders in Operating Partnership
Balance at Dec. 31, 2018	$ 1,669,632	$ 75,000	$ 1,122	$ 2,118,179	$ (584,979)	$ 4,481	$ 1,613,803	$ 55,829
Balance (in shares) at Dec. 31, 2018			112,165,786
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accoutning Principle in Period of Adoption	(214)				(214)		(214)
Proceeds from sales of common stock, net	568,077		$ 201	567,876			568,077
Proceeds from sales of common stock (in shares)			19,997,332
Dividends, Common Stock					(136,595)
Dividends							(136,595)
Dividends and Distributions, Net	(141,842)
Distribution Made to Limited Partner, Cash Distributions Declared								(5,247)
Non-cash compensation activity, net	5,994			2,198			1,826	4,168
Non-cash compensation activity (in shares)			134,188
Non-cash compensation activity (in excess of earnings)			$ (1)		(373)
Redemption of common units to common stock			$ (6)	(9,232)			(9,238)	(9,238)
Redemption of common units to common stock (in shares)			661,082
Rebalancing of noncontrolling interest				(10,367)			(10,367)	10,367
Other comprehensive income	(29,441)					(28,511)	(28,511)	(930)
Net income	32,749				31,837		31,837	912
Balance at Sep. 30, 2019	2,104,955	75,000	$ 1,330	2,687,118	(690,324)	(24,030)	2,049,094	55,861
Balance (in shares) at Sep. 30, 2019			132,958,388
Balance at Dec. 31, 2018	1,669,632	75,000	$ 1,122	2,118,179	(584,979)	4,481	1,613,803	$ 55,829
Balance (in shares) at Dec. 31, 2018			112,165,786
Increase (Decrease) in Stockholders' Equity
Redemption of common units to common stock (in shares)								0
Balance at Dec. 31, 2019	2,363,891	75,000	$ 1,428	2,970,553	(723,027)	(18,426)	2,305,528	$ 58,363
Balance (in shares) at Dec. 31, 2019			142,815,593
Balance at Jun. 30, 2019	1,963,252	75,000	$ 1,264	2,501,013	(653,759)	(17,771)	1,905,747	57,505
Balance (in shares) at Jun. 30, 2019			126,372,945
Increase (Decrease) in Stockholders' Equity
Proceeds from sales of common stock, net	183,212		$ 64	183,148			183,212
Proceeds from sales of common stock (in shares)			6,375,129
Dividends, Common Stock					(47,465)
Dividends							(47,465)
Dividends and Distributions, Net	(48,840)
Distribution Made to Limited Partner, Cash Distributions Declared								(1,375)
Non-cash compensation activity, net	2,576			1,675			1,675	901
Non-cash compensation activity (in shares)			3,162
Non-cash compensation activity (in excess of earnings)			$ 0		0
Redemption of common units to common stock			$ (2)	(3,001)			(3,003)	(3,003)
Redemption of common units to common stock (in shares)			207,152
Rebalancing of noncontrolling interest				(1,719)			(1,719)	1,719
Other comprehensive income	(6,435)					(6,259)	(6,259)	(176)
Net income	11,190				10,900		10,900	290
Balance at Sep. 30, 2019	2,104,955	75,000	$ 1,330	2,687,118	(690,324)	(24,030)	2,049,094	55,861
Balance (in shares) at Sep. 30, 2019			132,958,388
Balance at Dec. 31, 2019	2,363,891	75,000	$ 1,428	2,970,553	(723,027)	(18,426)	2,305,528	58,363
Balance (in shares) at Dec. 31, 2019			142,815,593
Increase (Decrease) in Stockholders' Equity
Proceeds from sales of common stock, net	172,635		$ 56	172,579			172,635
Proceeds from sales of common stock (in shares)			5,600,000
Dividends, Common Stock					(164,712)
Dividends							(164,712)
Dividends and Distributions, Net	(169,124)
Distribution Made to Limited Partner, Cash Distributions Declared								4,412
Non-cash compensation activity, net	7,272			3,084			2,695	4,577
Non-cash compensation activity (in shares)			81,316
Non-cash compensation activity (in excess of earnings)			$ (1)		(390)
Redemption of common units to common stock			$ (7)	(11,535)			(11,542)	$ (11,542)
Redemption of common units to common stock (in shares)			730,104					0
Rebalancing of noncontrolling interest				(2,480)			(2,480)	$ 2,480
Other comprehensive income	(27,273)					(26,629)	(26,629)	(644)
Net income	108,563				106,092		106,092	2,471
Balance at Sep. 30, 2020	2,455,964	75,000	$ 1,492	3,155,271	(782,037)	(45,055)	2,404,671	51,293
Balance (in shares) at Sep. 30, 2020			149,227,013
Balance at Jun. 30, 2020	2,480,317	75,000	$ 1,489	3,148,163	(750,770)	(49,837)	2,424,045	56,272
Balance (in shares) at Jun. 30, 2020			148,941,121
Increase (Decrease) in Stockholders' Equity
Proceeds from sales of common stock, net	(21)		$ 0	(21)			(21)
Proceeds from sales of common stock (in shares)			0
Dividends, Common Stock					(55,010)
Dividends							(55,010)
Dividends and Distributions, Net	(56,421)
Distribution Made to Limited Partner, Cash Distributions Declared								(1,411)
Non-cash compensation activity, net	2,953			1,972			1,972	981
Non-cash compensation activity (in shares)			3,518
Non-cash compensation activity (in excess of earnings)			$ 0		0
Redemption of common units to common stock			$ (3)	(4,453)			(4,456)	(4,456)
Redemption of common units to common stock (in shares)			282,374
Rebalancing of noncontrolling interest				704			704	(704)
Other comprehensive income	4,927					4,782	4,782	145
Net income	24,209				23,743		23,743	466
Balance at Sep. 30, 2020	$ 2,455,964	$ 75,000	$ 1,492	$ 3,155,271	$ (782,037)	$ (45,055)	$ 2,404,671	$ 51,293
Balance (in shares) at Sep. 30, 2020			149,227,013