SOI Fixed Maturity AFS maturity aging (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Amortized cost
Maturing in one year or less	$ 567,095
Maturing after one year through five years	3,583,929
Maturing after five years through ten years	4,098,780
Maturing after ten years	5,203,246
Mortgage-backed and asset-backed securities	5,500,094
Total fixed maturities	18,953,144	17,807,359
Estimated fair value
Maturing in one year or less	595,521
Maturing after one year through five years	3,887,276
Maturing after five years through ten years	4,331,464
Maturing after ten years	5,636,566
Mortgage-backed and asset-backed securities	5,711,251
Total fixed maturities	$ 20,162,078	$ 18,469,544