Equity (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		$ 3,137	$ 636	$ 2,064
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		2,859	3,358	(1,926)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(36)	(178)	153
Other Comprehensive Income (Loss), Tax		(601)	(679)	349
Balance, end of year		5,359	3,137	636
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		(92)	(169)	(86)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		14	80	(60)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0	0	0
Other Comprehensive Income (Loss), Tax		9	(3)	(19)
Balance, end of year		(69)	(92)	(169)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	[1]	3,299	856	2,201
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	[1]	2,854	3,306	(1,861)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	42	182	(148)
Other Comprehensive Income (Loss), Tax	[1]	(611)	(681)	368
Balance, end of year	[1]	5,500	3,299	856
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		(70)	(51)	(51)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(9)	(28)	(5)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(6)	(4)	(5)
Other Comprehensive Income (Loss), Tax		1	5	0
Balance, end of year		(72)	(70)	(51)
Accounting Standards Update 2018-02 [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Stockholders' Equity, Other		$ (12)	$ 0	(3)
Accounting Standards Update 2018-02 [Member] | Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Stockholders' Equity, Other				(4)
Accounting Standards Update 2018-02 [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Stockholders' Equity, Other	[1]			0
Accounting Standards Update 2018-02 [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Stockholders' Equity, Other				0
Accounting Standards Update 2018-02 [Member] | Accumulated Other Comprehensive Income Member
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Stockholders' Equity, Other				$ (4)

[1] Includes cash flow hedges of $(49), $(26) and $9 as of December 31, 2020, 2019 and 2018, respectively. See Note 5 for additional information on cash flow hedges.