Summary of Investments - SOI Fixed Maturity AFS aging (Details 2) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized cost
Maturing in one year or less	$ 820,721
Maturing after one year through five years	3,782,417
Maturing after five years through ten years	7,151,808
Maturing after ten years	5,035,008
Mortgage-backed and asset-backed securities	4,602,550
Amortized cost	21,392,504	$ 21,672,727
Estimated fair value
Maturing in one year or less	836,028
Maturing after one year through five years	3,958,581
Maturing after five years through ten years	7,354,724
Maturing after ten years	5,366,623
Mortgage-backed and asset-backed securities	4,726,562
Estimated fair value	$ 22,242,518	$ 22,153,703