Summary of Investments - SOI Fixed Maturity AFS aging (Details 2) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Amortized cost
Maturing in one year or less	$ 691,217
Maturing after one year through five years	3,663,240
Maturing after five years through ten years	5,699,079
Maturing after ten years	5,023,933
Mortgage-backed and asset-backed securities	4,807,000
Amortized cost	19,884,469	$ 20,007,462
Estimated fair value
Maturing in one year or less	716,630
Maturing after one year through five years	3,892,707
Maturing after five years through ten years	5,940,455
Maturing after ten years	5,288,230
Mortgage-backed and asset-backed securities	5,000,157
Estimated fair value	$ 20,838,179	$ 20,531,627