Fair Value of Assets and Liabilities (Details 6) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financial assets
Mortgage loans	$ 4,338	$ 4,188
Financial liabilities
Long-term debt	5,124	5,140
Liability for collateral	840	782	$ 624	$ 808
Carrying value
Financial assets
Mortgage loans	4,338	4,188
Cost method limited partnerships	1,154	1,122
Bank loans	1,565	1,663
Agent loans	422	368
Financial liabilities
Contractholder funds on investment contracts	12,424	13,734
Long-term debt	5,124	5,140
Liability for collateral	840	782
Fair value
Financial assets
Mortgage loans	4,489	4,446
Cost method limited partnerships	1,450	1,488
Bank loans	1,527	1,638
Agent loans	408	361
Financial liabilities
Contractholder funds on investment contracts	12,874	14,390
Long-term debt	5,648	5,835
Liability for collateral	$ 840	$ 782