Long-Term Debt - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Long-term finance leases and equipment financing	$ 67	$ 119
Total long-term debt	23,272	18,839
Fair Value Hedges
Debt Instrument [Line Items]
Decrease in carrying value of long-term debt	$ 220	184
Parent Company and Non-banking Subsidiaries | Senior notes | 3.55% Notes due 2025
Debt Instrument [Line Items]
Interest rate on debt	3.55%
Long-term debt	$ 1,285	1,265
Parent Company and Non-banking Subsidiaries | Senior notes | 5.272% Notes due 2026
Debt Instrument [Line Items]
Interest rate on debt	5.272%
Long-term debt	$ 1,203	1,211
Parent Company and Non-banking Subsidiaries | Senior notes | 4.330% Notes Due 2027
Debt Instrument [Line Items]
Interest rate on debt	4.33%
Long-term debt	$ 1,189	0
Parent Company and Non-banking Subsidiaries | Senior notes | 4.993% Notes Due 2027
Debt Instrument [Line Items]
Interest rate on debt	4.993%
Long-term debt	$ 993	0
Parent Company and Non-banking Subsidiaries | Senior notes | 2.400% notes due 2030
Debt Instrument [Line Items]
Interest rate on debt	2.40%
Long-term debt	$ 784	790
Parent Company and Non-banking Subsidiaries | Senior notes | 2.65% notes due 2026
Debt Instrument [Line Items]
Interest rate on debt	2.65%
Long-term debt	$ 728	719
Parent Company and Non-banking Subsidiaries | Senior notes | Floating Rate Notes Due 2026
Debt Instrument [Line Items]
Long-term debt	299	299
Parent Company and Non-banking Subsidiaries | Senior notes | Floating Rate Notes Due 2027
Debt Instrument [Line Items]
Long-term debt	$ 299	0
Parent Company and Non-banking Subsidiaries | Senior notes | 7.35% notes due 2026
Debt Instrument [Line Items]
Interest rate on debt	7.35%
Long-term debt	$ 150	150
Parent Company and Non-banking Subsidiaries | Senior notes | 3.300% Senior Notes Due 2024
Debt Instrument [Line Items]
Interest rate on debt	3.30%
Long-term debt	$ 0	977
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 5.104% Notes Due 2026
Debt Instrument [Line Items]
Interest rate on debt	5.104%
Long-term debt	$ 999	998
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 5.159% Notes Due 2034
Debt Instrument [Line Items]
Interest rate on debt	5.159%
Long-term debt	$ 995	995
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.530% Notes Due 2029
Debt Instrument [Line Items]
Interest rate on debt	4.53%
Long-term debt	$ 989	0
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 5.684% Notes Due 2029
Debt Instrument [Line Items]
Interest rate on debt	5.684%
Long-term debt	$ 986	995
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.675% Notes Due 2032
Debt Instrument [Line Items]
Interest rate on debt	4.675%
Long-term debt	$ 789	0
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.821% Notes Due 2034
Debt Instrument [Line Items]
Interest rate on debt	4.821%
Long-term debt	$ 702	731
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.164% notes due 2033
Debt Instrument [Line Items]
Interest rate on debt	4.164%
Long-term debt	$ 665	687
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 2.203% notes due 2028
Debt Instrument [Line Items]
Interest rate on debt	2.203%
Long-term debt	$ 619	605
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.141% notes due 2029
Debt Instrument [Line Items]
Interest rate on debt	4.141%
Long-term debt	$ 535	556
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.857% Notes due 2034
Debt Instrument [Line Items]
Interest rate on debt	4.857%
Long-term debt	$ 499	496
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 5.751% notes due 2026
Debt Instrument [Line Items]
Interest rate on debt	5.751%
Long-term debt	$ 498	497
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 3.152% notes due 2031
Debt Instrument [Line Items]
Interest rate on debt	3.152%
Long-term debt	$ 498	498
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 4.421% notes due 2033
Debt Instrument [Line Items]
Interest rate on debt	4.421%
Long-term debt	$ 498	497
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 1.684% notes due 2027
Debt Instrument [Line Items]
Interest rate on debt	1.684%
Long-term debt	$ 497	496
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 2.901% notes due 2026
Debt Instrument [Line Items]
Interest rate on debt	2.901%
Long-term debt	$ 497	485
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 5.82% notes due 2028
Debt Instrument [Line Items]
Interest rate on debt	5.82%
Long-term debt	$ 495	497
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 2.623% notes due 2023
Debt Instrument [Line Items]
Interest rate on debt	2.623%
Long-term debt	$ 465	476
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 1.746% notes due 2026
Debt Instrument [Line Items]
Interest rate on debt	1.746%
Long-term debt	$ 299	290
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 2.354% notes due 2025
Debt Instrument [Line Items]
Interest rate on debt	2.354%
Long-term debt	$ 0	972
Parent Company and Non-banking Subsidiaries | Senior subordinated notes | 2.200% notes due 2031
Debt Instrument [Line Items]
Interest rate on debt	2.20%
Long-term debt	$ 845	845
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior subordinated notes | 3.031% notes due 2034
Debt Instrument [Line Items]
Interest rate on debt	3.031%
Long-term debt	$ 523	528
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior subordinated notes | 6.123% Notes Due 2034
Debt Instrument [Line Items]
Interest rate on debt	6.123%
Long-term debt	$ 492	497
Parent Company and Non-banking Subsidiaries | Junior subordinated debentures | Floating-rate subordinated debentures due 2047
Debt Instrument [Line Items]
Long-term debt	500	500
Parent Company and Non-banking Subsidiaries | Junior subordinated debentures | Floating Rate Subordinated Debentures Due 2028
Debt Instrument [Line Items]
Long-term debt	100	100
State Street Bank
Debt Instrument [Line Items]
Long-term finance leases and equipment financing	$ 116	187
State Street Bank | Senior notes | 4.594% Senior Notes Due 2026
Debt Instrument [Line Items]
Interest rate on debt	4.594%
Long-term debt	$ 1,146	0
State Street Bank | Senior notes | 4.782% Senior Notes Due 2029
Debt Instrument [Line Items]
Interest rate on debt	4.782%
Long-term debt	$ 796	0
State Street Bank | Senior notes | Floating Rate Senior Notes Due 2026
Debt Instrument [Line Items]
Long-term debt	$ 299	$ 0