Summary of Investments - SOI Fixed Maturity AFS aging (Details 2) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Amortized cost
Maturing in one year or less	$ 664,969
Maturing after one year through five years	3,560,986
Maturing after five years through ten years	4,865,732
Maturing after ten years	5,162,877
Mortgage-backed and asset-backed securities	2,858,347
Total fixed maturities	17,112,911	$ 18,953,144
Estimated fair value
Maturing in one year or less	692,965
Maturing after one year through five years	3,839,087
Maturing after five years through ten years	5,019,172
Maturing after ten years	5,393,104
Mortgage-backed and asset-backed securities	3,032,749
Total fixed maturities	$ 17,977,077	$ 20,162,078