Consolidated Statements Of Shareholders' Equity - USD ($) $ in Millions	Total	Common Shares	Common Shares in Treasury	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]	Cumulative Translation Adjustment	Accumulated Defined Benefit Plans Adjustment [Member]	Accumulated Other Comprehensive Income
Balance – beginning of year at Dec. 31, 2018		$ 11,121	$ (2,618)	$ 12,557	$ 31,700	$ (12)	$ 31,688	$ (545)	$ (1,976)	$ 73
Treasury Stock, Retired, Cost Method, Amount		0	0		0
Common Shares repurchased			(1,531)
Net shares redeemed under employee share-based compensation plans			395	(178)
Stock Issued During Period, Value, Stock Options Exercised				(82)
Share-based compensation expense				266
FundingDividendsDeclaredToRetainedEarnings				(1,360)
Net income	$ 4,454				4,454
Funding Dividends Declared From Additional Paid In Capital					1,360
Dividends declared on Common Shares					(1,360)
Change in year, before reclassification from AOCI, net of income tax (expense) benefit of $527, $(426), and $(647)								3,057
Amounts reclassified from AOCI, net of income tax (expense) of $(6), $(36), and nil								31
Change in year, net of income tax (expense) benefit of $521, $(462), and $(647)								3,088
Change in year, net of income tax (expense) benefit of $21, $(4), and $24									37
Change in year, net of income tax (expense) benefit of $(115), $50, and $18										(58)
Balance – Ending of year at Dec. 31, 2019	55,331	11,121	(3,754)	11,203	36,142	(72)	36,070	2,543	(1,939)	15	$ 619
Treasury Stock, Retired, Cost Method, Amount		(57)	323		(266)
Common Shares repurchased			(516)
Net shares redeemed under employee share-based compensation plans			303	(195)
Stock Issued During Period, Value, Stock Options Exercised				(50)
Share-based compensation expense				255
FundingDividendsDeclaredToRetainedEarnings				(1,398)
Net income	3,533				3,533
Funding Dividends Declared From Additional Paid In Capital					1,398
Dividends declared on Common Shares					(1,398)
Change in year, before reclassification from AOCI, net of income tax (expense) benefit of $527, $(426), and $(647)								1,885
Amounts reclassified from AOCI, net of income tax (expense) of $(6), $(36), and nil								245
Change in year, net of income tax (expense) benefit of $521, $(462), and $(647)								2,130
Change in year, net of income tax (expense) benefit of $21, $(4), and $24									302
Change in year, net of income tax (expense) benefit of $(115), $50, and $18										(182)
Balance – Ending of year at Dec. 31, 2020	59,441	11,064	(3,644)	9,815	39,337	$ 0	$ 39,337	4,673	(1,637)	(167)	2,869
Treasury Stock, Retired, Cost Method, Amount		(79)	590		(511)
Common Shares repurchased			(4,861)
Net shares redeemed under employee share-based compensation plans			451	(179)
Stock Issued During Period, Value, Stock Options Exercised				(52)
Share-based compensation expense				286
FundingDividendsDeclaredToRetainedEarnings				(1,392)
Net income	8,539				8,539
Funding Dividends Declared From Additional Paid In Capital					1,392
Dividends declared on Common Shares					(1,392)
Change in year, before reclassification from AOCI, net of income tax (expense) benefit of $527, $(426), and $(647)								(2,408)
Amounts reclassified from AOCI, net of income tax (expense) of $(6), $(36), and nil								(9)
Change in year, net of income tax (expense) benefit of $521, $(462), and $(647)								(2,417)
Change in year, net of income tax (expense) benefit of $21, $(4), and $24									(509)
Change in year, net of income tax (expense) benefit of $(115), $50, and $18										407
Balance – Ending of year at Dec. 31, 2021	$ 59,714	$ 10,985	$ (7,464)	$ 8,478	$ 47,365			$ 2,256	$ (2,146)	$ 240	$ 350