Regulatory Capital (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$ 29,073	$ 27,957
Capital ratio: required common equity tier 1 capital	8.00%	8.00%
Capital ratio: required tier 1 capital	0.095	0.095
Capital ratio: required total capital	0.115	0.115
Tier 1 leverage capital ratio, minimum	0.040	0.040
Capital conservation buffer	0.025
Stress capital buffer	2.50%
Global systemically important bank	0.010
Countercyclical capital buffer	0
Leverage ratio minimum	0.05
Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,227	$ 11,245
Retained earnings	29,073	27,957
Accumulated other comprehensive income (loss)	(1,625)	(2,354)
Treasury stock, at cost	(15,663)	(15,025)
Total	23,012	21,823
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,531)	(8,470)
Other adjustments	(410)	(382)
Common equity tier 1 capital	14,071	12,971
Preferred stock	2,816	1,976
Tier 1 capital	16,887	14,947
Qualifying subordinated long-term debt	1,867	1,870
Allowance for credit losses	0	0
Total capital	18,754	16,817
Credit risk	61,857	61,210
Operational risk	48,788	43,768
Market risk	2,150	2,475
Total risk-weighted assets	112,795	107,453
Adjusted quarterly average assets	$ 305,699	$ 269,807
Common equity tier 1 capital	12.50%	12.10%
Tier 1 capital	0.150	0.139
Total capital	0.166	0.157
Tier 1 leverage capital ratio, actual	0.055	0.055
Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,227	$ 11,245
Retained earnings	29,073	27,957
Accumulated other comprehensive income (loss)	(1,625)	(2,354)
Treasury stock, at cost	(15,663)	(15,025)
Total	23,012	21,823
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,531)	(8,470)
Other adjustments	(410)	(382)
Common equity tier 1 capital	14,071	12,971
Preferred stock	2,816	1,976
Tier 1 capital	16,887	14,947
Qualifying subordinated long-term debt	1,867	1,870
Allowance for credit losses	171	150
Total capital	18,925	16,967
Credit risk	118,987	109,228
Market risk	2,150	2,475
Total risk-weighted assets	121,137	111,703
Adjusted quarterly average assets	$ 305,699	$ 269,807
Common equity tier 1 capital	11.60%	11.60%
Tier 1 capital	0.139	0.134
Total capital	0.156	0.152
Tier 1 leverage capital ratio, actual	0.055	0.055
State Street Bank | Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 13,333	$ 13,033
Retained earnings	15,373	14,454
Accumulated other comprehensive income (loss)	(1,390)	(2,097)
Treasury stock, at cost	0	0
Total	27,316	25,390
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,258)	(8,208)
Other adjustments	(302)	(298)
Common equity tier 1 capital	18,756	16,884
Preferred stock	0	0
Tier 1 capital	18,756	16,884
Qualifying subordinated long-term debt	532	536
Allowance for credit losses	1	0
Total capital	19,289	17,420
Credit risk	56,595	54,942
Operational risk	46,863	42,297
Market risk	2,150	2,475
Total risk-weighted assets	105,608	99,714
Adjusted quarterly average assets	$ 302,212	$ 266,818
Common equity tier 1 capital	17.80%	16.90%
Tier 1 capital	0.178	0.169
Total capital	0.183	0.175
Tier 1 leverage capital ratio, actual	0.062	0.063
State Street Bank | Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 13,333	$ 13,033
Retained earnings	15,373	14,454
Accumulated other comprehensive income (loss)	(1,390)	(2,097)
Treasury stock, at cost	0	0
Total	27,316	25,390
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,258)	(8,208)
Other adjustments	(302)	(298)
Common equity tier 1 capital	18,756	16,884
Preferred stock	0	0
Tier 1 capital	18,756	16,884
Qualifying subordinated long-term debt	532	536
Allowance for credit losses	171	150
Total capital	19,459	17,570
Credit risk	116,847	107,067
Market risk	2,150	2,475
Total risk-weighted assets	118,997	109,542
Adjusted quarterly average assets	$ 302,212	$ 266,818
Common equity tier 1 capital	15.80%	15.40%
Tier 1 capital	0.158	0.154
Total capital	0.164	0.160
Tier 1 leverage capital ratio, actual	0.062	0.063