Shareholders' Equity - Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 24,431	$ 24,737	$ 22,270
Other comprehensive income (loss) before reclassifications		1,002	569
Reclassification of certain tax effects			(84)
Amounts reclassified into (out of) earnings		61	(5)
Other comprehensive income (loss)			480
Other comprehensive income (loss)		1,063	564	(347)
Ending balance		26,200	24,431	24,737
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(876)	(1,356)	(1,009)
Reclassification of certain tax effects	[1]		(84)
Other comprehensive income (loss)		1,063	564	(347)
Ending balance		187	(876)	(1,356)
Net Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(70)	(89)
Other comprehensive income (loss) before reclassifications		75	13
Reclassification of certain tax effects			(6)
Amounts reclassified into (out of) earnings		52	12
Other comprehensive income (loss)			19
Other comprehensive income (loss)		127
Ending balance		57	(70)	(89)
Net Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		409	(175)
Other comprehensive income (loss) before reclassifications		439	563
Reclassification of certain tax effects			21
Amounts reclassified into (out of) earnings		0	0
Other comprehensive income (loss)			584
Other comprehensive income (loss)		439
Ending balance		848	409	(175)
Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		46	16
Other comprehensive income (loss) before reclassifications		(250)	33
Reclassification of certain tax effects			(3)
Amounts reclassified into (out of) earnings		0	0
Other comprehensive income (loss)			30
Other comprehensive income (loss)		(250)
Ending balance		(204)	46	16
Other-Than-Temporary Impairment on Held-to-Maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(2)	(2)
Other comprehensive income (loss) before reclassifications		0	2
Reclassification of certain tax effects			(1)
Amounts reclassified into (out of) earnings		0	(1)
Other comprehensive income (loss)			0
Other comprehensive income (loss)		0
Ending balance		(2)	(2)	(2)
Net Unrealized Losses on Retirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(187)	(143)
Other comprehensive income (loss) before reclassifications		0	0
Reclassification of certain tax effects			(28)
Amounts reclassified into (out of) earnings		9	(16)
Other comprehensive income (loss)			(44)
Other comprehensive income (loss)		9
Ending balance		(178)	(187)	(143)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(1,072)	(963)
Other comprehensive income (loss) before reclassifications		738	(42)
Reclassification of certain tax effects			(67)
Amounts reclassified into (out of) earnings		0	0
Other comprehensive income (loss)			(109)
Other comprehensive income (loss)		738
Ending balance		$ (334)	$ (1,072)	$ (963)

[1] Represents the reclassification from accumulated other comprehensive income into retained earnings as a result of our adoption of ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income in the first quarter of 2019.