Investments (Securities in a gross unrealized loss position) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 9,256	$ 1,819
Gross Unrealized Losses, Less than 12 Months	388	27
Estimated Fair Value, 12 Months or Longer	544	866
Gross Unrealized Losses, 12 Months or Longer	144	128
Estimated Fair Value, Total	9,800	2,685
Gross Unrealized Losses, Total	532	155
Corporate and other bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	3,592	846
Gross Unrealized Losses, Less than 12 Months	129	13
Estimated Fair Value, 12 Months or Longer	72	108
Gross Unrealized Losses, 12 Months or Longer	6	8
Estimated Fair Value, Total	3,664	954
Gross Unrealized Losses, Total	135	21
States, municipalities and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	3,251	254
Gross Unrealized Losses, Less than 12 Months	197	5
Estimated Fair Value, 12 Months or Longer	129	165
Gross Unrealized Losses, 12 Months or Longer	75	39
Estimated Fair Value, Total	3,380	419
Gross Unrealized Losses, Total	272	44
Residential mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	1,293	583
Gross Unrealized Losses, Less than 12 Months	29	5
Estimated Fair Value, 12 Months or Longer	343	452
Gross Unrealized Losses, 12 Months or Longer	63	66
Estimated Fair Value, Total	1,636	1,035
Gross Unrealized Losses, Total	92	71
Commercial mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	640	85
Gross Unrealized Losses, Less than 12 Months	22	2
Estimated Fair Value, 12 Months or Longer		141
Gross Unrealized Losses, 12 Months or Longer		15
Estimated Fair Value, Total	640	226
Gross Unrealized Losses, Total	22	17
Other asset-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	269
Gross Unrealized Losses, Less than 12 Months	3
Estimated Fair Value, 12 Months or Longer
Gross Unrealized Losses, 12 Months or Longer
Estimated Fair Value, Total	269
Gross Unrealized Losses, Total	3
Total asset-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	2,202	668
Gross Unrealized Losses, Less than 12 Months	54	7
Estimated Fair Value, 12 Months or Longer	343	593
Gross Unrealized Losses, 12 Months or Longer	63	81
Estimated Fair Value, Total	2,545	1,261
Gross Unrealized Losses, Total	117	88
U.S. Treasury and obligations of government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	13	23
Gross Unrealized Losses, Less than 12 Months	1	1
Estimated Fair Value, 12 Months or Longer
Gross Unrealized Losses, 12 Months or Longer
Estimated Fair Value, Total	13	23
Gross Unrealized Losses, Total	1	1
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	111
Gross Unrealized Losses, Less than 12 Months	3
Estimated Fair Value, 12 Months or Longer
Gross Unrealized Losses, 12 Months or Longer
Estimated Fair Value, Total	111
Gross Unrealized Losses, Total	3
Redeemable preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months		28
Gross Unrealized Losses, Less than 12 Months		1
Estimated Fair Value, 12 Months or Longer
Gross Unrealized Losses, 12 Months or Longer
Estimated Fair Value, Total		28
Gross Unrealized Losses, Total		1
Total fixed maturity securities available-for-sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	9,169	1,819
Gross Unrealized Losses, Less than 12 Months	384	27
Estimated Fair Value, 12 Months or Longer	544	866
Gross Unrealized Losses, 12 Months or Longer	144	128
Estimated Fair Value, Total	9,713	2,685
Gross Unrealized Losses, Total	528	155
Preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	87
Gross Unrealized Losses, Less than 12 Months	4
Estimated Fair Value, 12 Months or Longer
Gross Unrealized Losses, 12 Months or Longer
Estimated Fair Value, Total	87
Gross Unrealized Losses, Total	$ 4