Equity (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		$ 636	$ 2,064	$ 1,139
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		3,358	(1,926)	1,062
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(178)	153	(29)
Other Comprehensive Income (Loss), Tax		(679)	349	(265)
Balance, end of year		3,137	636	2,064
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		(169)	(86)	(172)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		80	(60)	27
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0	0	0
Other Comprehensive Income (Loss), Tax		(3)	(19)	42
Balance, end of year		(92)	(169)	(86)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	[1]	856	2,201	1,355
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	[1]	3,306	(1,861)	1,039
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	182	(148)	34
Other Comprehensive Income (Loss), Tax	[1]	(681)	368	(307)
Balance, end of year	[1]	3,299	856	2,201
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		(51)	(51)	(44)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(28)	(5)	(4)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(4)	(5)	(5)
Other Comprehensive Income (Loss), Tax		5	0	0
Balance, end of year		(70)	(51)	(51)
Accounting Standards Update 2018-02 [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		0	(3)	18
Accounting Standards Update 2018-02 [Member] | Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			(4)	17
Accounting Standards Update 2018-02 [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	[1]		0	148
Accounting Standards Update 2018-02 [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0	(8)
Accounting Standards Update 2018-02 [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ (4)	$ 157

[1] Includes cash flow hedges of $(26), $9 and $3 as of December 31, 2019, 2018 and 2017, respectively. See Note 5 for additional information on cash flow hedges.