CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 541	$ 533	$ 1,776	$ 1,443
Other Comprehensive Income (Loss), Net of Tax
Change in Unrealized Appreciation of Investments	(3)	229	(699)	350
Change in Unrealized Other-Than-Temporary Impairment Losses on Investments				2
Foreign Currency Translation Gains (Losses)	(41)	20	(63)	(17)
Change in Postretirement Benefit Costs Not Yet Recognized in Net Income	15	12	46	40
Total Other Comprehensive Income (Loss) Net of Tax	(29)	261	(716)	375
Comprehensive Income	$ 512	$ 794	$ 1,060	$ 1,818