Shares and Stockholders' Equity (Components And Changes In Accumulated OCI) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Components And Changes In Accumulated Other Comprehensive Income [Line Items]
Balance as of beginning-of-year	$ 1,566
Increases Attributable To
Gross OTTI recognized in OCI during the year		$ (26)
Less:
Balance as of end-of-period	1,847
Unrealized Gain (Loss) on AFS Securities [Member]
Components And Changes In Accumulated Other Comprehensive Income [Line Items]
Balance as of beginning-of-year	1,784	991
Unrealized holding gains (losses) arising during the year	530	2,469
Change in foreign currency exchange rate adjustment	19	7
Change in DAC, VOBA, DSI, future contract benefits and other contract holder funds	(121)	(661)
Income tax benefit (expense)	(151)	(641)
Less:
Reclassification adjustment for gains (losses) included in net income (loss)	(3)	(44)
Associated amortization of DAC, VOBA, DSI, and DFEL	(7)	(2)
Income tax benefit (expense)	4	16
Less:
Balance as of end-of-period	2,067	2,195
Unrealized OTTI on AFS Securities [Member]
Components And Changes In Accumulated Other Comprehensive Income [Line Items]
Balance as of beginning-of-year	25	26
Increases Attributable To
Gross OTTI recognized in OCI during the year		(26)
Change in DAC, VOBA, DSI and DFEL		6
Income tax benefit (expense)		7
Decreases attributable to
Changes in fair value, sales, maturities or other settlements of AFS securities	7	(14)
Change in DAC, VOBA, DSI, and DFEL	(1)	4
Income tax benefit (expense)	(2)	3
Less:
Balance as of end-of-period	29	6
Unrealized Gain (Loss) on Derivative Instruments [Member]
Components And Changes In Accumulated Other Comprehensive Income [Line Items]
Balance as of beginning-of-year	49	132
Change in foreign currency exchange rate adjustment	(20)	(11)
Decreases attributable to
Unrealized holding gains (losses) arising during the year	20	(129)
Change in DAC, VOBA, DSI and DFEL	(2)	(4)
Income tax benefit (expense)	1	50
Less:
Reclassification adjustment for gains (losses) included in net income (loss)	7	7
Associated amortization of DAC, VOBA, DSI and DFEL		(1)
Income tax benefit (expense)	(2)	(2)
Balance as of end-of-period	43	34
Foreign Currency Translation Adjustment [Member]
Components And Changes In Accumulated Other Comprehensive Income [Line Items]
Balance as of beginning-of-year	(27)	(5)
Change in foreign currency exchange rate adjustment	2	(2)
Less:
Balance as of end-of-period	(25)	(7)
Funded Status of Employee Benefit Plans [Member]
Components And Changes In Accumulated Other Comprehensive Income [Line Items]
Balance as of beginning-of-year	(265)	(299)
Less:
Adjustment arising during the period	(2)	2
Balance as of end-of-period	$ (267)	$ (297)