Summary of Investments - SOI Fixed Maturity AFS aging (Details 2) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Amortized cost
Maturing in one year or less	$ 628,975
Maturing after one year through five years	3,832,723
Maturing after five years through ten years	5,867,161
Maturing after ten years	5,059,694
Mortgage-backed and asset-backed securities	3,459,677
Amortized cost	18,848,230	$ 20,007,462
Estimated fair value
Maturing in one year or less	655,798
Maturing after one year through five years	4,104,021
Maturing after five years through ten years	6,263,431
Maturing after ten years	5,478,203
Mortgage-backed and asset-backed securities	3,669,135
Estimated fair value	$ 20,170,588	$ 20,531,627