Shares and Stockholders' Equity (Components And Changes In Accumulated OCI) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year	$ 3,230
Less:
Balance as of end-of-period	1,201
Unrealized Gain (Loss) on AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year	3,486	$ 1,784
Cumulative effect from adoption of new accounting standards			$ 674
Unrealized holding gains (losses) arising during the period	(4,891)	2,058
Change in foreign currency exchange rate adjustment	(50)	69
Change in DAC, VOBA, DSI, future contract benefits and other contract holder funds	1,395	(356)
Income tax benefit (expense)	749	(626)
Less:
Reclassification adjustment for gains (losses) included in net income (loss)	(29)	(13)
Associated amortization of DAC, VOBA, DSI, and DFEL	(10)	(11)
Income tax benefit (expense)	8	8
Less:
Balance as of end-of-period	1,394	2,945
Unrealized OTTI on AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year	44	25
Cumulative effect from adoption of new accounting standards			9
Decreases attributable to
Changes in fair value, sales, maturities or other settlements of AFS securities	(7)	21
Change in DAC, VOBA, DSI, and DFEL	(11)	(4)
Income tax benefit (expense)	4	(6)
Less:
Balance as of end-of-period	39	36
Unrealized Gain (Loss) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year	(29)	49
Cumulative effect from adoption of new accounting standards			(6)
Unrealized holding gains (losses) arising during the period	87	46
Change in foreign currency exchange rate adjustment	50	(75)
Decreases attributable to
Change in DAC, VOBA, DSI and DFEL	4	(8)
Income tax benefit (expense)	(29)	13
Less:
Reclassification adjustment for gains (losses) included in net income (loss)	11	7
Associated amortization of DAC, VOBA, DSI and DFEL	(1)	(2)
Income tax benefit (expense)	(2)	(2)
Balance as of end-of-period	69	22
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year	(14)	(27)
Change in foreign currency exchange rate adjustment	(4)	7
Less:
Balance as of end-of-period	(18)	(20)
Funded Status of Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning-of-year	(257)	(265)
Cumulative effect from adoption of new accounting standards			$ (35)
Less:
Adjustment arising during the period	9	(7)
Balance as of end-of-period	$ (283)	$ (272)