Fair Value Measurements (Details 4) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Financial assets:
Cash and cash equivalents		$ 1,231	$ 1,220	$ 1,212	$ 1,343
Mortgage loans		1,097	1,067
Policy loans		198	201
Financial liabilities:
Long-term debt		998	998
Level 1 [Member]
Financial assets:
Cash and cash equivalents		1,231	1,220
Mortgage loans		0	0
Policy loans		0	0
Total financial assets not accounted for at fair value		1,231	1,220
Financial liabilities:
Annuity benefits accumulated	[1]	0	0
Long-term debt		0	0
Total financial liabilities not accounted for at fair value		0	0
Level 2 [Member]
Financial assets:
Cash and cash equivalents		0	0
Mortgage loans		0	0
Policy loans		0	0
Total financial assets not accounted for at fair value		0	0
Financial liabilities:
Annuity benefits accumulated	[1]	0	0
Long-term debt		1,110	1,105
Total financial liabilities not accounted for at fair value		1,110	1,105
Level 3 [Member]
Financial assets:
Cash and cash equivalents		0	0
Mortgage loans		1,108	1,074
Policy loans		198	201
Total financial assets not accounted for at fair value		1,306	1,275
Financial liabilities:
Annuity benefits accumulated	[1]	27,210	25,488
Long-term debt		15	15
Total financial liabilities not accounted for at fair value		27,225	25,503
Carrying Value [Member]
Financial assets:
Cash and cash equivalents		1,231	1,220
Mortgage loans		1,097	1,067
Policy loans		198	201
Total financial assets not accounted for at fair value		2,526	2,488
Financial liabilities:
Annuity benefits accumulated	[1]	27,613	26,422
Long-term debt		1,006	1,000
Total financial liabilities not accounted for at fair value		28,619	27,422
Fair Value [Member]
Financial assets:
Cash and cash equivalents		1,231	1,220
Mortgage loans		1,108	1,074
Policy loans		198	201
Total financial assets not accounted for at fair value		2,537	2,495
Financial liabilities:
Annuity benefits accumulated	[1]	27,210	25,488
Long-term debt		1,125	1,120
Total financial liabilities not accounted for at fair value		$ 28,335	$ 26,608

[1] Excludes $199 million and $200 million of life contingent annuities in the payout phase at March 31, 2016 and December 31, 2015, respectively.