Stockholders’ Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	May 29, 2019	Apr. 23, 2019	Mar. 29, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 28, 2015
Equity, Class of Treasury Stock [Line Items]
Common stock, authorized				300,000,000	300,000,000
Common stock, par value	$ 0.50			$ 0.50	$ 0.50
Preferred stock, shares authorized				1,770,819
Preferred stock, par value				$ 1.00
Common and preferred shares authorized							$ 500,000
Sale Of Stock, Shares	21,661,095
Common stock issued	$ 750,000			$ 557,389
Private Placement expenses	$ 21,560
Share Price			$ 34.62
Discount			4.50%
Transfer Restriction Period				15 months
Stock Purchase Contracts Settled				4,109,292
Stock Purchase Contracts Settled, Issuance Of Common Shares				4,846,601
Stock Purchase Contracts, Initial Principal Amount				$ 8.62909
Stock Purchase Contracts, Aggregate Initial Principal Amount				$ 119,081
Stock Purchase Contracts, Interest Rate				3.00%
Stock Purchase Contracts, Quarterly Cash Installments				$ 0.75000
Stock Purchase Contracts, Cash Installments				$ 0.80833
Stock Purchase Contracts, Interest And Partial Repayment				6.00%
Proceeds From Shares Issued, Gross				$ 570,919
Proceeds From Shares Issued, Issuance Costs				$ 13,530
Direct Stock Purchase Plan discount from current market value				5.00%
Issue of common shares under dividend reinvestment plan				236,666	158,205	45,121
Common stock sold under dividend reinvestment plan				$ 8,959	$ 5,163	$ 1,453
Shares available for issuance under acquisition shelf registration				487,155
Long-Term [Member]
Equity, Class of Treasury Stock [Line Items]
Debt issued				119,081
Debt issuance costs				$ 2,828
Investor [Member]
Equity, Class of Treasury Stock [Line Items]
Private Placement expenses			$ 4,000
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock issued		$ 1,293,750
Private Placement expenses		$ 30,651
Share Price		$ 34.62
Tangible Equity Units [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock issued		$ 690,000
Private Placement expenses		$ 16,358
Share Price		$ 50		$ 50
Dividend Reinvestment [Member]
Equity, Class of Treasury Stock [Line Items]
Shares purchased by transfer agent for dividend reinvestment plan				183,731	321,585	447,753
Value of shares purchased in open market for dividend investment plan				$ 7,777	$ 11,343	$ 15,168
Issue of common shares under dividend reinvestment plan				236,666	158,205,000
Common stock sold under dividend reinvestment plan				$ 8,959	$ 5,163
Minimum [Member] | Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Settle		1.1790
Maximum [Member] | Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Settle		$ 1.4442