Segment Information - Schedule of Reportable Operating Segments, Consolidated Revenue and Segment Operating Income (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)
Revenue
Total revenue	$ 3,997	$ 3,721	$ 12,881	$ 11,551
Expenses
Compensation and benefits	2,259	2,150	6,868	6,163
Information technology	140	141	412	397
Premises	85	88	252	241
Other Expenses	697	719	2,213	2,006
Total operating expenses	3,181	3,098	9,745	8,807
Operating income	$ 816	$ 623	$ 3,136	$ 2,744
Operating margin	0.204	0.167	0.243	0.238
Interest income	$ 0	$ 4	$ 5	$ 63
Interest expense	(206)	(213)	(624)	(582)
Other income (expense)	(13)	35	33	346
Income before income taxes	597	449	2,550	2,571
Risk Capital
Expenses
Investment income	72	83	201	234
Human Capital
Expenses
Investment income	3	2	7	5
Operating Segments | Risk Capital
Revenue
Total revenue	2,525	2,355	8,582	7,980
Expenses
Compensation and benefits	1,455	1,368	4,457	4,112
Information technology	94	93	272	275
Premises	56	57	162	161
Other Expenses	335	276	1,045	902
Total operating expenses	1,940	1,794	5,936	5,450
Operating income	$ 585	$ 561	$ 2,646	$ 2,530
Operating margin	0.232	0.238	0.308	0.317
Operating Segments | Human Capital
Revenue
Total revenue	$ 1,475	$ 1,369	$ 4,311	$ 3,597
Expenses
Compensation and benefits	776	740	2,346	1,977
Information technology	44	47	134	121
Premises	28	31	87	80
Other Expenses	295	349	892	740
Total operating expenses	1,143	1,167	3,459	2,918
Operating income	$ 332	$ 202	$ 852	$ 679
Operating margin	0.225	0.148	0.198	0.189
Corporate/Eliminations
Revenue
Total revenue	$ (3)	$ (3)	$ (12)	$ (26)
Expenses
Compensation and benefits	28	42	65	74
Information technology	2	1	6	1
Premises	1	0	3	0
Other Expenses	67	94	276	364
Total operating expenses	98	137	350	439
Operating income	$ (101)	$ (140)	$ (362)	$ (465)