Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 499	$ 579	$ 948	$ 1,235
Other Comprehensive Income (Loss), Net of Tax
Change in Unrealized Appreciation of Investments	238	(700)	473	(696)
Change in Postretirement Benefit Costs Not Yet Recognized in Net Income	5	14	11	31
Foreign Currency Translation Gains (Losses)	4	28	(15)	(22)
Total Other Comprehensive Income (Loss) Net of Tax	247	(658)	469	(687)
Comprehensive Income (Loss)	$ 746	$ (79)	$ 1,417	$ 548