Consolidated Statements Of Shareholders' Equity (USD $) In Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Net Unrealized Investment Gain (Loss) [Member]	Accumulated Translation Adjustment [Member]	Accumulated Defined Benefit Plans Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance - beginning of period at Dec. 31, 2011		$ 10,095	$ (327)	$ 5,326	$ 7,327	$ 1,715	$ 258	$ (62)
Dividends declared on Common Shares-par value reduction		(168)
Common Shares repurchased			(7)
Net shares redeemed under employee share-based compensation plans			128	(100)
Exercise of stock options				(12)
Share-based compensation expense and other				61
FundingDividendsDeclaredToRetainedEarnings				(200)
Net income	1,301				1,301
Funding of dividends declared from Additional paid-in capital					200
Dividends declared on Common Shares					(200)
Change in period, net of income tax benefit (expense) of $344 and $(96)						451
Change in period, net of income tax benefit of $62 and $5							(23)
Change in period, net of income tax (expense) of $(7) and nil								(1)
Balance - end of period at Jun. 30, 2012	25,762	9,927	(206)	5,075	8,628	2,166	235	(63)	2,338
Balance - beginning of period at Dec. 31, 2012	27,531	9,591	(159)	5,179	10,033	2,633	339	(85)
Dividends declared on Common Shares-par value reduction		(342)
Common Shares repurchased			(212)
Net shares redeemed under employee share-based compensation plans			152	(128)
Exercise of stock options				(28)
Share-based compensation expense and other				105
FundingDividendsDeclaredToRetainedEarnings				0
Net income	1,844				1,844
Funding of dividends declared from Additional paid-in capital					0
Dividends declared on Common Shares					0
Change in period, before reclassification from AOCI, net of income tax benefit of $332						(1,254)
Amounts reclassified from AOCI, net of income tax benefit of $12						(61)
Change in period, net of income tax benefit (expense) of $344 and $(96)						(1,315)
Change in period, net of income tax benefit of $62 and $5							(324)
Change in period, net of income tax (expense) of $(7) and nil								12
Balance - end of period at Jun. 30, 2013	$ 27,295	$ 9,249	$ (219)	$ 5,128	$ 11,877	$ 1,318	$ 15	$ (73)	$ 1,260