Accumulated Other Comprehensive Income (Loss) by Component (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	$ 831
Other comprehensive income (loss), before reclassifications	(388)
Amounts reclassified from accumulated other comprehensive income (loss)	1
Other comprehensive income (loss), net of tax	(389)
Accumulated other comprehensive income (loss), ending balance	442
Tax (expense) benefit on amounts reclassified from accumulated other comprehensive income (loss)	1
Tax (expense) benefit on other comprehensive income (loss)	203
Tax on cumulative foreign currency translation adjustment
Cumulative foreign currency translation adjustment		161
Tax on pension and postretirement benefits		387
Pension and postretirement benefits		(721)
Tax on net unrealized gains (losses) on investments with OTTI losses		(11)
Net unrealized gains (losses) on investments with OTTI losses		20
Tax on net unrealized gains (losses) on other investments		(721)
Net unrealized gains (losses) on other investments		1,371
Tax on accumulated other comprehensive income (loss)		(345)
Net unrealized gains (losses) on investments with OTTI losses [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	20
Other comprehensive income (loss), before reclassifications	6
Amounts reclassified from accumulated other comprehensive income (loss)
Other comprehensive income (loss), net of tax	6
Accumulated other comprehensive income (loss), ending balance	26
Tax (expense) benefit on amounts reclassified from accumulated other comprehensive income (loss)
Tax (expense) benefit on other comprehensive income (loss)	(3)
Net unrealized gains (losses) on other investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	1,371
Other comprehensive income (loss), before reclassifications	(658)
Amounts reclassified from accumulated other comprehensive income (loss)	21
Other comprehensive income (loss), net of tax	(679)
Accumulated other comprehensive income (loss), ending balance	692
Tax (expense) benefit on amounts reclassified from accumulated other comprehensive income (loss)	(10)
Tax (expense) benefit on other comprehensive income (loss)	364
Pension and postretirement benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(721)
Other comprehensive income (loss), before reclassifications	275
Amounts reclassified from accumulated other comprehensive income (loss)	(20)
Other comprehensive income (loss), net of tax	295
Accumulated other comprehensive income (loss), ending balance	(426)
Tax (expense) benefit on amounts reclassified from accumulated other comprehensive income (loss)	11
Tax (expense) benefit on other comprehensive income (loss)	(158)
Cumulative foreign currency translation adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	161
Other comprehensive income (loss), before reclassifications	(11)
Amounts reclassified from accumulated other comprehensive income (loss)
Other comprehensive income (loss), net of tax	(11)
Accumulated other comprehensive income (loss), ending balance	150
Tax (expense) benefit on amounts reclassified from accumulated other comprehensive income (loss)
Tax (expense) benefit on other comprehensive income (loss)