Fair Value of Assets and Liabilities (Details 6) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Financial assets
Mortgage loans	$ 4,343	$ 4,188
Financial liabilities
Long-term debt	5,186	5,194
Liability for collateral	751	782	$ 907	$ 624
Carrying value
Financial assets
Mortgage loans	4,343	4,188
Cost method limited partnerships	1,130	1,122
Bank loans	1,763	1,663
Agent loans	404	368
Financial liabilities
Contract holder funds on investment contracts	13,118	13,734
Long-term debt	5,186	5,194
Liability for collateral	751	782
Estimate of Fair Value Measurement [Member]
Financial assets
Mortgage loans	4,537	4,446
Cost method limited partnerships	1,482	1,488
Bank loans	1,754	1,638
Agent loans	393	361
Financial liabilities
Contract holder funds on investment contracts	13,680	14,390
Long-term debt	5,707	5,835
Liability for collateral	$ 751	$ 782