Shareholders' Equity - Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 25,191	$ 27,363	$ 26,200
Other comprehensive income (loss) before reclassifications	775	(2,700)	(1,255)
Increase (decrease) due to amounts reclassified from accumulated other comprehensive income	582	122	(65)
Other comprehensive income (loss)	1,357	(2,578)	(1,320)
Ending balance	23,799	25,191	27,363
Unrecognized gain (loss) in AOCI	(530)	(749)
Net Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(359)	(2)	57
Other comprehensive income (loss) before reclassifications	75	(321)	11
Increase (decrease) due to amounts reclassified from accumulated other comprehensive income	153	(36)	(70)
Other comprehensive income (loss)	228	(357)	(59)
Ending balance	(131)	(359)	(2)
Net Unrealized Gains (Losses) on Investment Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,817)	(50)	846
Other comprehensive income (loss) before reclassifications	442	(1,937)	(854)
Increase (decrease) due to amounts reclassified from accumulated other comprehensive income	428	170	(42)
Other comprehensive income (loss)	870	(1,767)	(896)
Ending balance	(947)	(1,817)	(50)
Net Unrealized Losses on Retirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(143)	(130)	(178)
Other comprehensive income (loss) before reclassifications	(3)	(1)	1
Increase (decrease) due to amounts reclassified from accumulated other comprehensive income	1	(12)	47
Other comprehensive income (loss)	(2)	(13)	48
Ending balance	(145)	(143)	(130)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,751)	(1,019)	(334)
Other comprehensive income (loss) before reclassifications	351	(732)	(685)
Increase (decrease) due to amounts reclassified from accumulated other comprehensive income	0	0	0
Other comprehensive income (loss)	351	(732)	(685)
Ending balance	(1,400)	(1,751)	(1,019)
Net Unrealized Gains (Losses) on Hedges of Net Investments in Non-U.S. Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	359	68	(204)
Other comprehensive income (loss) before reclassifications	(90)	291	272
Increase (decrease) due to amounts reclassified from accumulated other comprehensive income	0	0	0
Other comprehensive income (loss)	(90)	291	272
Ending balance	269	359	68
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,711)	(1,133)	187
Other comprehensive income (loss)	1,357	(2,578)	(1,320)
Ending balance	$ (2,354)	$ (3,711)	$ (1,133)