Long-Term Debt - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-term finance leases and equipment financing	$ 119	$ 167
Total long-term debt	18,839	14,996
Fair Value Hedges
Debt Instrument [Line Items]
Decrease in carrying value of long-term debt	$ 184	282
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	$ 1,265	1,256
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	$ 1,211	0
Parent Company and Non-banking Subsidiaries | Senior notes | 3.3% notes due 2024
Debt Instrument [Line Items]
Interest rate on debt	3.30%
Long-term debt	$ 977	962
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	$ 790	797
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	$ 719	709
Parent Company and Non-banking Subsidiaries | Senior notes | Floating Rate Notes Due 2026
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 | 3.700% Senior Notes Due 2023
Debt Instrument [Line Items]
Interest rate on debt	3.70%
Long-term debt	$ 0	985
Parent Company and Non-banking Subsidiaries | Subordinated notes | 3.100% Subordinated Notes Due 2023
Debt Instrument [Line Items]
Interest rate on debt	3.10%
Long-term debt	$ 0	1,006
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	$ 998	0
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	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	$ 995	0
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	$ 972	951
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	$ 731	0
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	$ 687	677
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	$ 605	589
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	$ 556	564
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	$ 497	498
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 | 5.82% notes due 2028
Debt Instrument [Line Items]
Interest rate on debt	5.82%
Long-term debt	$ 497	497
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	$ 497	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	$ 496	497
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	$ 496	0
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	$ 485	473
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	$ 476	466
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	$ 290	280
Parent Company and Non-banking Subsidiaries | Fixed-to-floating rate senior notes | 3.776% Fixed-to-Floating Rate Senior Notes Due 2024
Debt Instrument [Line Items]
Interest rate on debt	3.776%
Long-term debt	$ 0	492
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	844
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	$ 528	532
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	$ 497	0
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 notes due to State Street Capital Trust I in 2028
Debt Instrument [Line Items]
Long-term debt	100	100
State Street Bank
Debt Instrument [Line Items]
Long-term finance leases and equipment financing	$ 187	$ 176