Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' other comprehensive income (loss)	$ (146)	$ 55	$ 102	$ (288)
Other realized investment (gains) losses	(32)	(30)	(140)	(203)
Other operating expenses	2,080	1,933	6,156	5,739
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax	(85)	(4)	228	(424)
Reclassification adjustment, pre-tax	1	(16)	(28)	(109)
Other comprehensive income (loss), pre-tax	(84)	(20)	200	(533)
Other comprehensive income (loss), securities, before reclassifications, tax (expense) benefit	35	0	(70)	142
Reclassification adjustment, securities, tax (expense) benefit	0	6	10	38
Other comprehensive income (loss), tax (expense) benefit	35	6	(60)	180
Other comprehensive income (loss) before reclassifications, after-tax	(50)	(4)	158	(282)
Reclassification adjustment, after-tax	1	(10)	(18)	(71)
Shareholders' other comprehensive income (loss)	(49)	(14)	140	(353)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other realized investment (gains) losses	1	(16)	(28)	(109)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax	9	(4)	9	10
Other comprehensive income (loss), tax (expense) benefit	(3)	2	(3)	(3)
Shareholders' other comprehensive income (loss)	6	(2)	6	7
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax	(128)	68	(90)	(24)
Other comprehensive income (loss), tax (expense) benefit	15	(9)	12	9
Shareholders' other comprehensive income (loss)	(113)	59	(78)	(15)
Accumulated Defined Benefit Plans Adjustment Net Prior Service Cost Credit [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other operating expenses	13	19	41	53
Accumulated Defined Benefit Plans Adjustment Net Prior Service Cost Credit [Member] | Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment, pre-tax	13	19	41	53
Reclassification adjustment, postretirement benefits, tax (expense) benefit	(4)	(7)	(14)	(19)
Reclassification adjustment, after-tax	9	12	27	34
Accumulated Defined Benefit Plans Adjustment Curtailment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other operating expenses				(19)
Accumulated Defined Benefit Plans Adjustment Curtailment [Member] | Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment, pre-tax				(19)
Reclassification adjustment, postretirement benefits, tax (expense) benefit				7
Reclassification adjustment, after-tax				(12)
Accumulated Defined Benefit Plans Adjustment Settlement [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other operating expenses			6
Accumulated Defined Benefit Plans Adjustment Settlement [Member] | Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment, pre-tax			6
Reclassification adjustment, postretirement benefits, tax (expense) benefit			(2)
Reclassification adjustment, after-tax			4
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other operating expenses			47	34
Accumulated Defined Benefit Plans Adjustment [Member] | Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax	1		3	79
Reclassification adjustment, pre-tax			47	34
Other comprehensive income (loss), pre-tax	14	19	50	113
Reclassification adjustment, postretirement benefits, tax (expense) benefit			(16)	(12)
Other comprehensive income (loss), postretirement benefits, before reclassifications, tax (expense) benefit	0		(1)	(28)
Other comprehensive income (loss), tax (expense) benefit	(4)	(7)	(17)	(40)
Other comprehensive income (loss) before reclassifications, after-tax	1		2	51
Reclassification adjustment, after-tax			31	22
Shareholders' other comprehensive income (loss)	$ 10	$ 12	$ 33	$ 73