Capital Stock: (Schedule of Common Stock) (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Capital Stock [Roll Forward]
Shares issued, beginning of period (in shares)	2,109,316,331
Shares repurchased, beginning of period (in shares)	(559,146,338)
Shares issued, end of period (in shares)	2,109,316,331	2,109,316,331
Shares repurchased, end of period (in shares)	(559,098,620)	(559,146,338)
Shares Issued
Capital Stock [Roll Forward]
Shares issued, beginning of period (in shares)	2,109,316,331	2,109,316,331	2,109,316,331
Shares issued, end of period (in shares)	2,109,316,331	2,109,316,331	2,109,316,331
Shares Repurchased
Capital Stock [Roll Forward]
Shares repurchased, beginning of period (in shares)	(559,146,338)	(551,942,600)	(553,421,668)
Issuance of stock awards (in shares)	2,014,448	1,310,891	1,479,068
Repurchase of shares (in shares)	(1,966,730)	(8,514,629)
Shares repurchased, end of period (in shares)	(559,098,620)	(559,146,338)	(551,942,600)
Shares Outstanding
Capital Stock [Roll Forward]
Shares outstanding, beginning of period (in shares)	1,550,169,993	1,557,373,731	1,555,894,663
Issuance of stock awards (in shares)	2,014,448	1,310,891	1,479,068
Repurchase of shares (in shares)	(1,966,730)	(8,514,629)
Shares outstanding, end of period (in shares)	1,550,217,711	1,550,169,993	1,557,373,731