Summary of Investments - SOI Fixed Maturity AFS aging (Details 2) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Amortized cost
Maturing in one year or less	$ 591,644
Maturing after one year through five years	3,654,433
Maturing after five years through ten years	5,053,440
Maturing after ten years	5,337,099
Mortgage-backed and asset-backed securities	3,003,519
Total fixed maturities	17,640,135	$ 18,953,144
Estimated fair value
Maturing in one year or less	617,273
Maturing after one year through five years	3,917,068
Maturing after five years through ten years	5,204,264
Maturing after ten years	5,558,660
Mortgage-backed and asset-backed securities	3,197,089
Total fixed maturities	$ 18,494,354	$ 20,162,078