Regulatory Capital (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$ 28,166	$ 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	$ 11,228	$ 11,245
Retained earnings	28,166	27,957
Accumulated other comprehensive income (loss)	(2,369)	(2,354)
Treasury stock, at cost	(15,060)	(15,025)
Total	21,965	21,823
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,380)	(8,470)
Other adjustments	(418)	(382)
Common equity tier 1 capital	13,167	12,971
Preferred stock	2,468	1,976
Tier 1 capital	15,635	14,947
Qualifying subordinated long-term debt	1,869	1,870
Allowance for credit losses	0	0
Total capital	17,504	16,817
Credit risk	61,787	61,210
Operational risk	48,149	43,768
Market risk	2,225	2,475
Total risk-weighted assets	112,161	107,453
Adjusted quarterly average assets	$ 289,772	$ 269,807
Common equity tier 1 capital	11.70%	12.10%
Tier 1 capital	0.139	0.139
Total capital	0.156	0.157
Tier 1 leverage capital ratio, actual	0.054	0.055
Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,228	$ 11,245
Retained earnings	28,166	27,957
Accumulated other comprehensive income (loss)	(2,369)	(2,354)
Treasury stock, at cost	(15,060)	(15,025)
Total	21,965	21,823
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,380)	(8,470)
Other adjustments	(418)	(382)
Common equity tier 1 capital	13,167	12,971
Preferred stock	2,468	1,976
Tier 1 capital	15,635	14,947
Qualifying subordinated long-term debt	1,869	1,870
Allowance for credit losses	146	150
Total capital	17,650	16,967
Credit risk	116,388	109,228
Market risk	2,225	2,475
Total risk-weighted assets	118,613	111,703
Adjusted quarterly average assets	$ 289,772	$ 269,807
Common equity tier 1 capital	11.10%	11.60%
Tier 1 capital	0.132	0.134
Total capital	0.149	0.152
Tier 1 leverage capital ratio, actual	0.054	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	14,888	14,454
Accumulated other comprehensive income (loss)	(2,094)	(2,097)
Treasury stock, at cost	0	0
Total	26,127	25,390
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,107)	(8,208)
Other adjustments	(321)	(298)
Common equity tier 1 capital	17,699	16,884
Preferred stock	0	0
Tier 1 capital	17,699	16,884
Qualifying subordinated long-term debt	535	536
Allowance for credit losses	0	0
Total capital	18,234	17,420
Credit risk	54,966	54,942
Operational risk	47,044	42,297
Market risk	2,225	2,475
Total risk-weighted assets	104,235	99,714
Adjusted quarterly average assets	$ 286,577	$ 266,818
Common equity tier 1 capital	17.00%	16.90%
Tier 1 capital	0.170	0.169
Total capital	0.175	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	14,888	14,454
Accumulated other comprehensive income (loss)	(2,094)	(2,097)
Treasury stock, at cost	0	0
Total	26,127	25,390
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,107)	(8,208)
Other adjustments	(321)	(298)
Common equity tier 1 capital	17,699	16,884
Preferred stock	0	0
Tier 1 capital	17,699	16,884
Qualifying subordinated long-term debt	535	536
Allowance for credit losses	146	150
Total capital	18,380	17,570
Credit risk	114,292	107,067
Market risk	2,225	2,475
Total risk-weighted assets	116,517	109,542
Adjusted quarterly average assets	$ 286,577	$ 266,818
Common equity tier 1 capital	15.20%	15.40%
Tier 1 capital	0.152	0.154
Total capital	0.158	0.160
Tier 1 leverage capital ratio, actual	0.062	0.063