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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 4	$ 0	$ 9	$ (15)
Total recurring Level 3 liabilities	0	7	3	(8)
Fair value, assets and liabilities gain (loss) included in earnings	9	7	17	(9)
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	4	7	12	(23)
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	2	(4)	3	(22)
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	4	7	7
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	(1)	(7)	(6)	(6)
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	1	14	8	(2)
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	0	7	3	(8)
Corporate
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	0	3	0	1
Equity securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	2	(4)	7	(16)
Free-standing derivatives, net
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	2	1	3	0
Other assets
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 0	$ 0	$ (1)	$ 0