Fair Value of Assets and Liabilities (Change In Unrealized Gains and Losses included in Net Income for Level 3) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ (1)	$ 5	$ 8	$ (10)
Total recurring Level 3 liabilities	(8)	(2)	(5)	(10)
Fair value, assets and liabilities gain (loss) included in earnings	(6)	3	11	(6)
Gain (loss) on investments
Gains (losses) included in net income for Level 3 assets and liabilities:
Fair value, assets and liabilities gain (loss) included in earnings	(9)	3	3	(20)
Realized capital gains and losses
Gains (losses) included in net income for Level 3 assets and liabilities:
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	(3)	3		(19)
(Loss) gain reclassified from AOCI into income (net investment income)
Gains (losses) included in net income for Level 3 assets and liabilities:
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	2	2	9	9
Interest credited to contractholder funds
Gains (losses) included in net income for Level 3 assets and liabilities:
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	(4)	(5)	(10)	(11)
Contract benefits
Gains (losses) included in net income for Level 3 assets and liabilities:
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	(4)	3	4	1
Contractholder funds: Derivatives embedded in life and annuity contracts
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 liabilities	(8)	(2)	(5)	(10)
Municipal
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	0	1	0	1
Corporate
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	1	0	1	1
Fixed income securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	1	1	1	2
Equity securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	1	0	8	(16)
Free-standing derivatives, net
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	(3)	4	0	4
Other assets
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 0	$ 0	$ (1)	$ 0