Consolidated Statements Of Shareholders' Equity (USD $) In Millions	Common Shares [Member]	Common Shares In Treasury [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Deferred Compensation Obligation [Member]	Net Unrealized Appreciation (Depreciation) On Investments [Member]	Cumulative Translation Adjustment [Member]	Pension Liability Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Shares Issued To Employee Trust [Member]	Total
Balance - beginning of period at Dec. 31, 2009	$ 10,503	$ (3)	$ 5,526	$ 2,818	$ 2	$ 657	$ 240	$ (74)		$ (2)
Net shares issued (redeemed) under employee share-based compensation plans	71		(59)
Exercise of stock options	20		11
Dividends declared on Common Shares-par value reduction	(330)
Common Shares issued in treasury, net of net shares redeemed under employee share-based compensation plans		(30)
Share-based compensation expense and other			101
Net income (loss)				2,107							2,107
Accumulated other comprehensive income (loss)
Change in period, net of income tax expense of $(112) and $(366)						1,311
Change in period, net of income tax (expense) benefit of $(30) and $48							(25)
Change in period, net of income tax benefit (expense) of $1 and $(1)								1
Balance - end of period at Sep. 30, 2010	10,264	(33)	5,579	4,925	2	1,968	215	(73)	2,110	(2)	22,845
Balance - beginning of period at Dec. 31, 2010	10,161	(330)	5,623	5,926	2	1,399	262	(67)		(2)	22,974
Net shares issued (redeemed) under employee share-based compensation plans			(111)
Exercise of stock options	47		26
Common Shares repurchased		(100)
Dividends declared on Common Shares-par value reduction	(113)
Common Shares issued in treasury, net of net shares redeemed under employee share-based compensation plans		80
Share-based compensation expense and other			103
Funding of dividends declared to Retained earnings			(236)
Net income (loss)				835							835
Funding of dividends declared from Additional paid-in capital				236
Dividends declared on Common Shares				(236)
Accumulated other comprehensive income (loss)
Change in period, net of income tax expense of $(112) and $(366)						127
Change in period, net of income tax (expense) benefit of $(30) and $48							119
Change in period, net of income tax benefit (expense) of $1 and $(1)								(1)
Balance - end of period at Sep. 30, 2011	$ 10,095	$ (350)	$ 5,405	$ 6,761	$ 2	$ 1,526	$ 381	$ (68)	$ 1,839	$ (2)	$ 23,750