CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 579	$ 404	$ 1,235	$ 910
Other Comprehensive Income (Loss), Net of Tax
Change in Unrealized Appreciation of Investments	(700)	67	(696)	121
Change in Unrealized Other-Than-Temporary Impairment Losses on Investments		1		2
Foreign Currency Translation Gains (Losses)	28	(28)	(22)	(37)
Change in Postretirement Benefit Costs Not Yet Recognized in Net Income	14	14	31	28
Total Other Comprehensive Income (Loss) Net of Tax	(658)	54	(687)	114
Comprehensive Income (Loss)	$ (79)	$ 458	$ 548	$ 1,024