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
	Mar. 31, 2017	Mar. 31, 2016
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ 5	$ (15)
Total recurring Level 3 liabilities	3	(15)
Fair value, assets and liabilities gain (loss) included in earnings	8	(16)
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	8	(30)
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	1	(18)
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	5	3
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	(5)	1
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	7	(16)
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	3	(15)
Corporate
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	0	(2)
Equity securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	5	(12)
Free-standing derivatives, net
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	1	(1)
Other assets
Gains (losses) included in net income for Level 3 assets and liabilities:
Total recurring Level 3 assets	$ (1)	$ 0