CONDENSED 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 (Deficit)	Retained Earnings (Deficit) Series E Preferred Stock	Retained Earnings (Deficit) Series F Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Balances 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	225,822			225,394							225,394				428
Dividends declared and paid:
Preferred stock dividends declared and paid		$ (12,291)	$ (13,455)		$ (12,291)	$ (13,455)						$ (12,291)	$ (13,455)
Common stock dividends declared and paid	(229,403)			(229,403)					3	16,168	(245,574)
Issuance of common stock:
Director compensation	968			968						968
Stock purchase plan	309			309						309
ATM equity program	127,337			127,337					24	127,313
Equity offering	395,500			395,500					70	395,430
Restricted shares, net of forfeitures									4	(4)
Stock issuance costs	(17,480)			(17,480)						(17,480)
Amortization of deferred compensation	6,841			6,841						6,841
Amortization of interest rate hedges	975			975										975
Fair value of forward starting swaps	(11,738)			(11,738)										(11,738)
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)
Balances at Sep. 30, 2019	4,626,504			4,626,497			287,500	345,000	1,717	4,479,600	(469,646)			(17,674)	7
Balances at Jun. 30, 2019	4,222,451			4,222,449			287,500	345,000	1,636	4,042,318	(443,822)			(10,183)	2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	66,698			66,693							66,693				5
Dividends declared and paid:
Preferred stock dividends declared and paid		$ (4,097)	(4,485)		$ (4,097)	(4,485)						$ (4,097)	(4,485)
Common stock dividends declared and paid	(74,715)			(74,715)					1	9,219	(83,935)
Issuance of common stock:
Director compensation	325			325						325
Stock purchase plan	94			94						93
ATM equity program	46,524			46,524					8	46,516
Equity offering	395,500			395,500					70	395,430
Restricted shares, net of forfeitures									1	(1)
Stock issuance costs	(16,714)			(16,714)						(16,714)
Amortization of deferred compensation	2,414			2,414						2,414
Amortization of interest rate hedges	327			327										327
Fair value of forward starting swaps	(7,818)			(7,818)										(7,818)
Valuation adjustments – available-for-sale securities	0
Realized gain – available-for-sale securities	0
Balances at Sep. 30, 2019	4,626,504			4,626,497			$ 287,500	345,000	1,717	4,479,600	(469,646)			(17,674)	7
Balances 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	167,509			167,512							167,512				(3)
Dividends declared and paid:
Preferred stock dividends declared and paid			(13,455)			(13,455)							(13,455)
Common stock dividends declared and paid	(262,066)			(262,066)					1	4,298	(266,365)
Issuance of common stock:
Director compensation	865			865					1	864
Stock purchase plan	238			238						238
ATM equity program	60,902			60,902					16	60,886
Restricted shares, net of forfeitures									3	(3)
Stock issuance costs	(1,230)			(1,230)						(1,230)
Amortization of deferred compensation	8,718			8,718						8,718
Amortization of interest rate hedges	1,663			1,663										1,663
Fair value of forward starting swaps	(7,617)			(7,617)										(7,617)
Valuation adjustments – available-for-sale securities	0
Realized gain – available-for-sale securities	0
Balances at Sep. 30, 2020	4,287,209			4,287,205				345,000	1,739	4,569,085	(611,537)			(17,082)	4
Balances at Jun. 30, 2020	4,310,800			4,310,795				345,000	1,735	4,554,958	(573,174)			(17,724)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	56,068			56,069							56,069				(1)
Dividends declared and paid:
Preferred stock dividends declared and paid			$ (4,485)			$ (4,485)							$ (4,485)
Common stock dividends declared and paid	(86,799)			(86,799)					1	3,147	(89,947)
Issuance of common stock:
Director compensation	269			269					1	268
Stock purchase plan	68			68						68
ATM equity program	8,139			8,139					2	8,137
Stock issuance costs	(484)			(484)						(484)
Amortization of deferred compensation	2,991			2,991						2,991
Amortization of interest rate hedges	642			642										642
Fair value of forward starting swaps	0
Valuation adjustments – available-for-sale securities	0
Realized gain – available-for-sale securities	0
Balances at Sep. 30, 2020	$ 4,287,209			$ 4,287,205				$ 345,000	$ 1,739	$ 4,569,085	$ (611,537)			$ (17,082)	$ 4