Consolidated Statments of Comprehensive Income and Changes in Shareholders' Equity (USD $) In Millions	Total	Shareholder Comprehensive Income Loss And Shareholders Equity [Member]	Common Stock	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income	Retained Earnings	Treasury Stock	Noncontrolling Interest
Total Comprehensive Income and Total Equity, beginning of period at Dec. 31, 2008			$ 88	$ 2,502	$ (1,074)	$ 7,374	$ (5,298)	$ 6
Additional Paid In Capital, Effects of stock issuance for employee benefit plans				12
Accumulated Other Comprehensive Loss, Implementation effect of updated guidance on other than temporary impairments					(18)
Net unrealized appreciation (depreciation), fixed maturities					543
Net unrealized appreciation (depreciation), equity securities					(3)
Net unrealized appreciation (depreciation) on securities	540
Net unrealized appreciation (depreciation), derivatives	(17)				(17)
Net translation of foreign currencies	48				48
Postretirement benefit liability adjustment	(97)				(97)
Shareholders' net income	1,302					1,302
Retained Earnings, Effects of stock issuance for employee benefit plans						(58)
Retained Earnings, Implementation effect of updated guidance on other than temporary impairments						18
Common dividends declared (per share: $0.04; $0.04)						(11)
Repurchase of common stock
Other, primarily issuance of treasury stock for employee benefit plans							106
Net income attributable to noncontrolling interest	3							3
Accumulated other comprehensive income attributable to noncontrolling interest	2							3
Total Comprehensive Income and Total Equity, end of period at Dec. 31, 2009	5,429	5,417	88	2,514	(618)	8,625	(5,192)	12
Additional Paid In Capital, Effects of stock issuance for employee benefit plans				20
Accumulated Other Comprehensive Loss, Implementation effect of updated guidance on other than temporary impairments					0
Net unrealized appreciation (depreciation), fixed maturities					151
Net unrealized appreciation (depreciation), equity securities					(1)
Net unrealized appreciation (depreciation) on securities	150
Net unrealized appreciation (depreciation), derivatives	6				6
Net translation of foreign currencies	37				37
Postretirement benefit liability adjustment	(189)				(189)
Shareholders' net income	1,345					1,345
Retained Earnings, Effects of stock issuance for employee benefit plans						(80)
Retained Earnings, Implementation effect of updated guidance on other than temporary impairments	0
Common dividends declared (per share: $0.04; $0.04)						(11)
Repurchase of common stock							(201)
Other, primarily issuance of treasury stock for employee benefit plans							151
Net income attributable to noncontrolling interest	4							4
Accumulated other comprehensive income attributable to noncontrolling interest								2
Total Comprehensive Income and Total Equity, end of period at Dec. 31, 2010	6,663	6,645	88	2,534	(614)	9,879	(5,242)	18
Stock Issued During Period, Value, New Issues			4	625
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests				2				(19)
Additional Paid In Capital, Effects of stock issuance for employee benefit plans				27
Accumulated Other Comprehensive Loss, Implementation effect of updated guidance on other than temporary impairments					0
Net unrealized appreciation (depreciation), fixed maturities					210
Net unrealized appreciation (depreciation), equity securities					(2)
Net unrealized appreciation (depreciation) on securities	208
Net unrealized appreciation (depreciation), derivatives	1				1
Net translation of foreign currencies	(28)				(28)
Postretirement benefit liability adjustment	(360)				(360)
Shareholders' net income	1,327					1,327
Retained Earnings, Effects of stock issuance for employee benefit plans						(53)
Retained Earnings, Implementation effect of updated guidance on other than temporary impairments	0
Common dividends declared (per share: $0.04; $0.04)						(10)
Repurchase of common stock							(225)
Other, primarily issuance of treasury stock for employee benefit plans							181
Net income attributable to noncontrolling interest	1							1
Accumulated other comprehensive income attributable to noncontrolling interest								0
Total Comprehensive Income and Total Equity, end of period at Dec. 31, 2011	$ 8,344	$ 8,344	$ 92	$ 3,188	$ (793)	$ 11,143	$ (5,286)	$ 0