Stockholder's Equity (Summary of Stockholders' Equity Capital Accounts) (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Preferred Stock, $1.00 par value:
Preferred stock, par value (in USD per share)	$ 1.00	$ 1.00
Authorized shares (in shares)	50,000,000	50,000,000
Issued shares (in shares)	0	0
Outstanding shares (in shares)	0	0	14,369,965	14,370,060
Common Stock, $1.00 par value:
Common stock, par value (in USD per share)	$ 1.00	$ 1.00
Authorized shares (in shares)	700,000,000	700,000,000
Issued shares (in shares)	419,124,469	411,550,857
Outstanding shares (in shares)	417,400,602	410,256,615