Investments (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Amortized cost
Amortized cost, fixed maturities	$ 8,986
Estimated fair value
Estimated fair value, fixed maturities	9,465	8,688
Indemnity
Amortized cost
Due in one year or less	61
Due after one year through five years	237
Due after five years through ten years	146
Due after ten years	107
Amortized cost, fixed maturities	551	518
Estimated fair value
Due in one year or less	61
Due after one year through five years	239
Due after five years through ten years	151
Due after ten years	112
Estimated fair value, fixed maturities	563	526
Exchange
Amortized cost
Due in one year or less	380
Due after one year through five years	3,236
Due after five years through ten years	3,262
Due after ten years	1,557
Amortized cost, fixed maturities	8,435	7,801
Estimated fair value
Due in one year or less	387
Due after one year through five years	3,419
Due after five years through ten years	3,417
Due after ten years	1,679
Estimated fair value, fixed maturities	$ 8,902	$ 8,162