Summary of Significant Accounting Policies - Prior Period Adjustments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Condensed Consolidated Balance Sheets
Cash	$ 12,155		$ 13,477
Restricted cash	27,220		25,059
Securities purchased under agreements to resell	61,525		56,250
Condensed Consolidated Statements of Cash Flows
Net change in securities purchased under agreements to resell	(5,275)	$ 8,510
Net cash provided by (used in) investing activities	121,167	111,483
Net increase (decrease) in cash and restricted cash	839	3,941
Cash and restricted cash at beginning of period	38,536	33,981
Cash and restricted cash at end of period	$ 39,375	37,922
As Previously Reported
Condensed Consolidated Balance Sheets
Cash			38,853
Restricted cash			39,958
Securities purchased under agreements to resell			15,975
Condensed Consolidated Statements of Cash Flows
Net change in securities purchased under agreements to resell		12,635
Net cash provided by (used in) investing activities		115,608
Net increase (decrease) in cash and restricted cash		8,066
Cash and restricted cash at beginning of period		68,706
Cash and restricted cash at end of period		76,772
Adjustment for Change in Accounting Principle
Condensed Consolidated Balance Sheets
Cash			(25,376)
Restricted cash			(14,899)
Securities purchased under agreements to resell			$ 40,275
Condensed Consolidated Statements of Cash Flows
Net change in securities purchased under agreements to resell		(4,125)
Net cash provided by (used in) investing activities		(4,125)
Net increase (decrease) in cash and restricted cash		(4,125)
Cash and restricted cash at beginning of period		(34,725)
Cash and restricted cash at end of period		$ (38,850)