CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Series E Preferred Stock	Series F Preferred Stock	Total Stockholders’ Equity	Total Stockholders’ Equity Series E Preferred Stock	Total Stockholders’ Equity Series F Preferred Stock	Preferred Stock Series E Preferred Stock	Preferred Stock Series F Preferred Stock	Common Stock	Capital in Excess of Par Value	Retained Earnings (Loss)	Retained Earnings (Loss) Series E Preferred Stock	Retained Earnings (Loss) Series F Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance at Dec. 31, 2017	$ 3,840,910			$ 3,840,593			$ 287,500	$ 345,000	$ 1,537	$ 3,599,475	$ (379,181)			$ (13,738)	$ 317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	292,485			292,447							292,447				38
Dividends declared and paid:
Preferred stock dividends declared and paid		$ (16,387)	$ (17,940)		$ (16,387)	$ (17,940)						$ (16,387)	$ (17,940)
Common stock dividends declared and paid	(290,201)			(290,201)					3	12,960	(303,164)
Issuance of common stock:
Director compensation	1,375			1,375						1,375
Stock purchase plan	426			426						426
ATM equity program	332,018			332,018					74	331,944
Restricted shares - net of forfeitures and repurchases	(89)			(89)					2	(91)
Stock issuance costs	(3,947)			(3,947)						(3,947)
Amortization of deferred compensation	7,913			7,913						7,913
Amortization of interest rate hedges	3,664			3,664										3,664
Fair value of forward starting swaps	4,080			4,080										4,080
Valuation adjustments – available-for-sale securities	298			298										298
Realized gain – available-for-sale securities	0
Ending balance at Dec. 31, 2018	4,154,605			4,154,250			287,500	345,000	1,616	3,950,055	(424,225)			(5,696)	355
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	299,608			299,180							299,180				428
Dividends declared and paid:
Preferred stock dividends declared and paid		$ (13,201)	(17,940)		$ (13,201)	(17,940)						$ (13,201)	(17,940)
Common stock dividends declared and paid	(314,619)			(314,619)					4	19,069	(333,692)
Redemption of depositary shares	(287,500)			(287,500)			$ (287,500)			9,856	(9,856)
Issuance of common stock:
Director compensation	1,294			1,294						1,294
Stock purchase plan	370			370						370
ATM equity program	127,337			127,337					24	127,313
Equity offering	395,500			395,500					70	395,430
Restricted shares - net of forfeitures and repurchases	0			0					4	(4)
Stock issuance costs	(17,521)			(17,521)						(17,521)
Amortization of deferred compensation	9,452			9,452						9,452
Amortization of interest rate hedges	1,307			1,307										1,307
Fair value of forward starting swaps	(5,524)			(5,524)										(5,524)
Valuation adjustments – available-for-sale securities	116			116										116
Realized gain – available-for-sale securities	(1,331)			(1,331)										(1,331)
Other	505			505							505
Distributions to noncontrolling interests	(776)														(776)
Ending balance at Dec. 31, 2019	4,331,682			4,331,675				345,000	1,718	4,495,314	(499,229)			(11,128)	7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	228,796			228,799							228,799				(3)
Dividends declared and paid:
Preferred stock dividends declared and paid			$ (17,940)			$ (17,940)							$ (17,940)
Common stock dividends declared and paid	(351,544)			(351,544)					1	4,864	(356,409)
Issuance of common stock:
Director compensation	1,132			1,132						1,132
Stock purchase plan	308			308						308
ATM equity program	121,315			121,315					31	121,284
Restricted shares - net of forfeitures and repurchases	0			0					3	(3)
Stock issuance costs	(2,212)			(2,212)						(2,212)
Amortization of deferred compensation	13,084			13,084						13,084
Amortization of interest rate hedges	2,300			2,300										2,300
Fair value of forward starting swaps	(7,617)			(7,617)										(7,617)
Realized gain – available-for-sale securities	0
Ending balance at Dec. 31, 2020	$ 4,319,304			$ 4,319,300				$ 345,000	$ 1,753	$ 4,633,771	$ (644,779)			$ (16,445)	$ 4