Fair Value of Assets and Liabilities (Level 3 Assets and Liabilities)(Footnotes to Table) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, assets and liabilities gain (loss) included in earnings	$ 9	$ 7	$ 17	$ (9)
Total gains (losses) included in: Net income	9	0	14	(1)
Other investments: Free-standing derivatives	1	1	1	1
Free-standing derivatives, liabilities		8		8
Realized capital gains and losses
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total gains (losses) included in: Net income	7	(4)	8	(8)
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	2	(4)	3	(22)
Net investment income
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total gains (losses) included in: Net income	2	4	7	7
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	2	4	7	7
Interest credited to contractholder funds
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total gains (losses) included in: Net income	(1)	(7)	(6)	(6)
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	(1)	(7)	(6)	(6)
Contract benefits
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	$ 1	$ 14	$ 8	$ (2)