Equity (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Balance, Beginning of Period		$ 3,137	$ 636
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(2,613)	1,454
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		142	(14)
Other Comprehensive Income (Loss), Tax		(464)	311
Balance, End of Period		1,130	1,765
Accumulated Translation Adjustment [Member]
Balance, Beginning of Period		(92)	(169)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(112)	19
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		0	0
Other Comprehensive Income (Loss), Tax		(19)	3
Balance, End of Period		(223)	(147)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Balance, Beginning of Period	[1]	3,299	856
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[1]	(2,496)	1,437
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[1]	141	(15)
Other Comprehensive Income (Loss), Tax	[1]	(482)	314
Balance, End of Period	[1]	1,426	1,964
Accumulated Defined Benefit Plans Adjustment [Member]
Balance, Beginning of Period		(70)	(51)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(5)	(2)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		1	1
Other Comprehensive Income (Loss), Tax		(1)	0
Balance, End of Period		$ (73)	$ (52)

[1] Includes cash flow hedges of $(87) and $(26) as of March 31, 2020 and December 31, 2019, respectively, and $(1) and $9 as of March 31, 2019 and December 31, 2018, respectively. See Note 5 – “Derivative Instruments” for additional information on cash flow hedges.