Consolidated Statements Of Shareholders' Equity (USD $) In Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Deferred Compensation, Share-based Payments [Member]	Accumulated Net Unrealized Investment Gain (Loss) [Member]	Accumulated Translation Adjustment [Member]	Accumulated Defined Benefit Plans Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Shares Issued To Employee Trust [Member]
Cumulative effect of adjustment resulting from adoption of new accounting guidance at Dec. 31, 2010					$ (139)
Balance - beginning of period at Dec. 31, 2010		10,161	(330)	5,623	5,926	2	1,399	262	(67)		(2)
Balance - beginning of period at Dec. 31, 2010					5,787
Change in period, net of income tax expense of $(96) and $(60)							175
Change in period, net of income tax benefit (expense) of $5 and $(77)								224
Change in period, net of income tax benefit of nil and $1									(4)
Net shares redeemed under employee share-based compensation plans				(111)
Exercise of stock options		50		20
Common Shares issued in treasury, net of net shares redeemed under employee share-based compensation plans			80
Net income	844				844
Share-based compensation expense and other				71
Dividends declared on Common Shares-par value reduction		(113)
Funding of dividends declared from Additional paid-in capital				(119)	119
Dividends declared on Common Shares					(119)
Balance - end of period at Jun. 30, 2011	23,952	10,098	(250)	5,484	6,631		1,574	486	(71)	1,989
Balance - beginning of period at Dec. 31, 2011	24,332	10,095	(327)	5,326	7,327		1,715	258	(62)
Balance - beginning of period at Dec. 31, 2011					7,327
Change in period, net of income tax expense of $(96) and $(60)							451
Change in period, net of income tax benefit (expense) of $5 and $(77)								(23)
Change in period, net of income tax benefit of nil and $1									(1)
Net shares redeemed under employee share-based compensation plans				(100)
Common Shares repurchased			(7)
Exercise of stock options				(12)
Common Shares issued in treasury, net of net shares redeemed under employee share-based compensation plans			128
Net income	1,301				1,301
Share-based compensation expense and other				61
Dividends declared on Common Shares-par value reduction		(168)
Funding of dividends declared from Additional paid-in capital				(200)	200
Dividends declared on Common Shares					(200)
Balance - end of period at Jun. 30, 2012	$ 25,762	$ 9,927	$ (206)	$ 5,075	$ 8,628		$ 2,166	$ 235	$ (63)	$ 2,338