Fair Value Measurements (Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation
Beginning balance	$ 55	$ 20
Total gains or losses (realized/unrealized):
Included in net income	0	0
Included in other comprehensive income	(1)	1
Purchases	57	37
Sales	(3)	0
Transfers into Level 3	13	0
Transfers out of Level 3	(43)	(3)
Ending balance	78	55
Corporate Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation
Beginning balance	51	18
Total gains or losses (realized/unrealized):
Included in net income	0	0
Included in other comprehensive income	0	0
Purchases	57	36
Sales	(1)	0
Transfers into Level 3	13	0
Transfers out of Level 3	(42)	(3)
Ending balance	78	51
Taxable Fixed Maturities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation
Beginning balance	1	0
Total gains or losses (realized/unrealized):
Included in net income	0	0
Included in other comprehensive income	0	0
Purchases	0	1
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(1)	0
Ending balance	0	1
Nonredeemable Preferred Equities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation
Beginning balance	3	2
Total gains or losses (realized/unrealized):
Included in net income	0	0
Included in other comprehensive income	(1)	1
Purchases	0	0
Sales	(2)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	$ 0	$ 3