Investments (Details 2) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Amortized cost
Amortized cost, fixed maturities	$ 9,593
Estimated fair value
Estimated fair value, fixed maturities	9,933	$ 9,571
Indemnity
Amortized cost
Due in one year or less	70
Due after one year through five years	236
Due after five years through ten years	150
Due after ten years	97
Amortized cost, fixed maturities	553	555
Estimated fair value
Due in one year or less	70
Due after one year through five years	237
Due after five years through ten years	154
Due after ten years	100
Estimated fair value, fixed maturities	561	564
Exchange
Amortized cost
Due in one year or less	425
Due after one year through five years	3,270
Due after five years through ten years	3,842
Due after ten years	1,503
Amortized cost, fixed maturities	9,040	8,540
Estimated fair value
Due in one year or less	432
Due after one year through five years	3,437
Due after five years through ten years	3,932
Due after ten years	1,571
Estimated fair value, fixed maturities	$ 9,372	$ 9,007