Accumulated Other Comprehensive Income - Activity in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pretax unrealized losses	$ 355	$ 1,909	$ 1,789	$ 1,359
Other comprehensive income (loss), tax effect	(85)	(454)	(429)	(318)
Other comprehensive income (loss), net of tax	270	1,455	1,360	1,041
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	21,124	19,226	19,645	19,172
Other comprehensive income, net of tax	270	1,455	1,360	1,041
Ending balance	21,107	20,784	21,107	20,784
Compensation and benefits	(685)	(690)	(2,132)	(2,099)
Accumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss), net of tax	270	1,455	1,360	1,041
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(3,546)	(4,901)	(4,636)	(4,487)
Other comprehensive income, net of tax	270	1,455	1,360	1,041
Ending balance	(3,276)	(3,446)	(3,276)	(3,446)
Available-for-sale debt securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	305	1,241	1,175	1,001
Other comprehensive income (loss), before reclassifications, tax effect	(75)	(297)	(285)	(238)
Other comprehensive income (loss), before reclassifications, net activity	(230)	(944)	(890)	(763)
Reclassification adjustment, pre-tax activity	0	11	0	17
Reclassification adjustment, tax effect	0	(2)	0	(4)
Reclassification adjustment, net activity	0	9	0	13
Pretax unrealized losses	305	1,252	1,175	2,012
Other comprehensive income (loss), tax effect	(75)	(299)	(285)	(451)
Other comprehensive income (loss), net of tax	230	953	890	1,561
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(2,620)	(3,486)	(3,280)	(4,094)
Other comprehensive income, net of tax	230	953	890	1,561
Ending balance	(2,390)	(2,533)	(2,390)	(2,533)
Available-for-sale debt securities transferred to held-to-maturity securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity				(994)
Other comprehensive income (loss), before reclassifications, tax effect				209
Other comprehensive income (loss), before reclassifications, net activity				785
Reclassification adjustment, pre-tax activity	31	33	91	97
Reclassification adjustment, tax effect	(6)	(7)	(19)	(21)
Reclassification adjustment, net activity	25	26	72	76
Pretax unrealized losses	31	33	91	(897)
Other comprehensive income (loss), tax effect	(6)	(7)	(19)	188
Other comprehensive income (loss), net of tax	25	26	72	(709)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(637)	(735)	(684)	0
Other comprehensive income, net of tax	25	26	72	(709)
Ending balance	(612)	(709)	(612)	(709)
Cash flow hedge derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(25)	530	373	(29)
Other comprehensive income (loss), before reclassifications, tax effect	6	(127)	(89)	7
Other comprehensive income (loss), before reclassifications, net activity	19	(403)	(284)	22
Reclassification adjustment, pre-tax activity	43	91	149	270
Reclassification adjustment, tax effect	(10)	(21)	(36)	(62)
Reclassification adjustment, net activity	33	70	113	208
Pretax unrealized losses	18	621	522	241
Other comprehensive income (loss), tax effect	(4)	(148)	(125)	(55)
Other comprehensive income (loss), net of tax	14	473	397	186
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(271)	(659)	(654)	(372)
Other comprehensive income, net of tax	14	473	397	186
Ending balance	(257)	(186)	(257)	(186)
Net periodic benefit costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(1)		(1)
Other comprehensive income (loss), before reclassifications, tax effect	0		0
Other comprehensive income (loss), before reclassifications, net activity	1		1
Reclassification adjustment, pre-tax activity	2	1	2	1
Reclassification adjustment, tax effect	0	0	0	0
Reclassification adjustment, net activity	2	1	2	1
Pretax unrealized losses	1	1	1	1
Other comprehensive income (loss), tax effect	0	0	0	0
Other comprehensive income (loss), net of tax	1	1	1	1
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(16)	(17)	(16)	(17)
Other comprehensive income, net of tax	1	1	1	1
Ending balance	(15)	(16)	(15)	(16)
Other
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pretax unrealized losses	0	2	0	2
Other comprehensive income (loss), tax effect	0	0	0	0
Other comprehensive income (loss), net of tax	0	2	0	2
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(2)	(4)	(2)	(4)
Other comprehensive income, net of tax	0	2	0	2
Ending balance	(2)	(2)	(2)	(2)
Settlements | Reclassification out of AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Compensation and benefits	$ (1)	$ 0	$ (1)	$ 0