Investments (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Amortized cost
Total fixed maturities	$ 8,413
Estimated fair value
Estimated fair value, fixed maturities	8,881	8,688
Indemnity
Amortized cost
Due in one year or less	76
Due after one year through five years	237
Due after five years through ten years	100
Due after ten years	77
Total fixed maturities	490
Estimated fair value
Due in one year or less	77
Due after one year through five years	240
Due after five years through ten years	104
Due after ten years	81
Estimated fair value, fixed maturities	502	526
Exchange
Amortized cost
Due in one year or less	386
Due after one year through five years	3,052
Due after five years through ten years	2,941
Due after ten years	1,544
Total fixed maturities	7,923
Estimated fair value
Due in one year or less	393
Due after one year through five years	3,239
Due after five years through ten years	3,113
Due after ten years	1,634
Estimated fair value, fixed maturities	$ 8,379	$ 8,162