Consolidated Statements Of Changes In Common Shareholders' Equity - USD ($) $ in Millions	Common Shares [Member]	Paid-in-Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income/(Loss) (Note 10) [Member]	[1]	Total
Shareholders' equity, beginning balance at Dec. 31, 2016	$ 2,777	$ 4,421	$ 32,587	$ (18,581)	$ (1,272)		$ 19,932
Common shares, beginning balance at Dec. 31, 2016	1,111,000,000.0			(295,200,000)
Net income			10,712				10,712
Other comp. income/(loss)					131		131	[2]
Conversion, stock option exercises, forfeitures, and other	$ 1	55		$ 20			76
Conversion, stock option exercises, forfeitures, and other (shares)	400,000			1,100,000
Share repurchases (Note 19)				$ (4,013)			(4,013)
Share repurchases (Note 19) (shares)				(36,400,000)
Cash dividends declared			(1,982)				(1,982)
Shareholders' equity, ending balance at Dec. 31, 2017	$ 2,778	4,476	41,317	$ (22,574)	(1,141)		24,856
Common shares, ending balance at Dec. 31, 2017	1,111,400,000			(330,500,000)
Net income			5,966				5,966
Other comp. income/(loss)					26		26	[2]
Conversion, stock option exercises, forfeitures, and other	$ 1	65		$ 33			99
Conversion, stock option exercises, forfeitures, and other (shares)	300,000			1,100,000
Share repurchases (Note 19)		(92)		$ (8,133)			$ (8,225)
Share repurchases (Note 19) (shares)				(57,200,000)			(57,219,033)
Cash dividends declared			(2,299)				$ (2,299)
Reclassification due to ASU 2018-02 adoption			300		(300)
Shareholders' equity, ending balance at Dec. 31, 2018	$ 2,779	4,449	45,284	$ (30,674)	(1,415)		$ 20,423
Common shares, ending balance at Dec. 31, 2018	1,111,700,000			(386,600,000)			725,056,690
Net income			5,919				$ 5,919
Other comp. income/(loss)					59		59	[2]
Conversion, stock option exercises, forfeitures, and other	$ 1	46		$ 82			129
Conversion, stock option exercises, forfeitures, and other (shares)	300,000			1,700,000
Share repurchases (Note 19)		28		$ (5,832)			$ (5,804)
Share repurchases (Note 19) (shares)				(35,000,000.0)			(34,994,369)
Cash dividends declared			(2,598)				$ (2,598)
Shareholders' equity, ending balance at Dec. 31, 2019	$ 2,780	$ 4,523	$ 48,605	$ (36,424)	$ (1,356)		$ 18,128
Common shares, ending balance at Dec. 31, 2019	1,112,000,000.0			(419,900,000)			692,100,651

[1] AOCI = Accumulated Other Comprehensive Income/(Loss) (Note 10)

[2] Net of deferred taxes of ($15) million, ($22) million, and ($61) million during 2019, 2018, and 2017, respectively.