(Rollforward Of Common Stock Activity) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, beginning balance	448,900
Treasury stock, beginning balance	56,800
Common stock, ending balance	448,900	448,900
Treasury stock, ending balance	55,800	56,800
Issued
Class of Stock [Line Items]
Common stock, beginning balance	448,916	448,916	448,916
Issuance of stock for various plans, net	0	0	0
Repurchase of stock	0	0	0
Common stock, ending balance	448,916	448,916	448,916
Treasury
Class of Stock [Line Items]
Treasury stock, beginning balance	56,800	48,310	35,975
Issuance of stock for various plans, net	(2,010)	(3,416)	(1,721)
Repurchase of stock	1,027	11,906	14,056
Treasury stock, ending balance	55,817	56,800	48,310