Shares and Stockholders' Equity (Components And Changes In Accumulated OCI) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year		$ 1,566
Increases Attributable To
Gross OTTI recognized in OCI during the period	$ (10)		$ (36)
Less:
Balance as of end-of-period		2,711
Unrealized Gain (Loss) on AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year		1,784	991
Unrealized holding gains (losses) arising during the year		2,058	5,394
Change in foreign currency exchange rate adjustment		69	(33)
Change in DAC, VOBA, DSI, future contract benefits and other contract holder funds		(356)	(1,620)
Income tax benefit (expense)		(626)	(1,321)
Less:
Reclassification adjustment for gains (losses) included in net income (loss)		(13)	(101)
Associated amortization of DAC, VOBA, DSI, and DFEL		(11)	(7)
Income tax benefit (expense)		8	38
Less:
Balance as of end-of-period	3,481	2,945	3,481
Unrealized OTTI on AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year		25	26
Increases Attributable To
Gross OTTI recognized in OCI during the period			(36)
Change in DAC, VOBA, DSI and DFEL			8
Income tax benefit (expense)			10
Decreases attributable to
Changes in fair value, sales, maturities or other settlements of AFS securities		21	5
Change in DAC, VOBA, DSI, and DFEL		(4)	(1)
Income tax benefit (expense)		(6)	(2)
Less:
Balance as of end-of-period	10	36	10
Unrealized Gain (Loss) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year		49	132
Unrealized holding gains (losses) arising during the year		46	(208)
Change in foreign currency exchange rate adjustment		(75)	35
Decreases attributable to
Change in DAC, VOBA, DSI and DFEL		(8)	(6)
Income tax benefit (expense)		13	62
Less:
Reclassification adjustment for gains (losses) included in net income (loss)		7	9
Associated amortization of DAC, VOBA, DSI and DFEL		(2)	(1)
Income tax benefit (expense)		(2)	(3)
Balance as of end-of-period	10	22	10
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year		(27)	(5)
Change in foreign currency exchange rate adjustment		7	(13)
Less:
Balance as of end-of-period	(18)	(20)	(18)
Funded Status of Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year		(265)	(299)
Less:
Adjustment arising during the period		(7)	11
Balance as of end-of-period	$ (288)	$ (272)	$ (288)