Regulatory Capital (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$ 27,993	$ 27,028
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	$ 11,239	$ 11,234
Retained earnings	27,993	27,028
Accumulated other comprehensive income (loss)	(3,045)	(3,711)
Treasury stock, at cost	(14,542)	(11,336)
Total	21,645	23,215
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,352)	(8,545)
Other adjustments	(289)	(123)
Common equity tier 1 capital	13,004	14,547
Preferred stock	1,976	1,976
Tier 1 capital	14,980	16,523
Qualifying subordinated long-term debt	1,374	1,376
Allowance for credit losses	3	0
Total capital	16,357	17,899
Credit risk	62,206	61,108
Operational risk	42,677	42,763
Market risk	1,963	1,488
Total risk-weighted assets	106,846	105,359
Adjusted quarterly average assets	$ 259,086	$ 275,678
Common equity tier 1 capital	12.20%	13.80%
Tier 1 capital	0.140	0.157
Total capital	0.153	0.170
Tier 1 leverage capital ratio, actual	0.058	0.060
Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,239	$ 11,234
Retained earnings	27,993	27,028
Accumulated other comprehensive income (loss)	(3,045)	(3,711)
Treasury stock, at cost	(14,542)	(11,336)
Total	21,645	23,215
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,352)	(8,545)
Other adjustments	(289)	(123)
Common equity tier 1 capital	13,004	14,547
Preferred stock	1,976	1,976
Tier 1 capital	14,980	16,523
Qualifying subordinated long-term debt	1,374	1,376
Allowance for credit losses	134	120
Total capital	16,488	18,019
Credit risk	116,045	105,739
Market risk	1,963	1,488
Total risk-weighted assets	118,008	107,227
Adjusted quarterly average assets	$ 259,086	$ 275,678
Common equity tier 1 capital	11.00%	13.60%
Tier 1 capital	0.127	0.154
Total capital	0.140	0.168
Tier 1 leverage capital ratio, actual	0.058	0.060
State Street Bank | Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 13,033	$ 13,033
Retained earnings	15,407	16,975
Accumulated other comprehensive income (loss)	(2,756)	(3,428)
Treasury stock, at cost	0	0
Total	25,684	26,580
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,096)	(8,288)
Other adjustments	(206)	(19)
Common equity tier 1 capital	17,382	18,273
Preferred stock	0	0
Tier 1 capital	17,382	18,273
Qualifying subordinated long-term debt	538	542
Allowance for credit losses	3	0
Total capital	17,923	18,815
Credit risk	56,273	54,675
Operational risk	42,299	42,325
Market risk	1,963	1,488
Total risk-weighted assets	100,535	98,488
Adjusted quarterly average assets	$ 256,408	$ 273,220
Common equity tier 1 capital	17.30%	18.60%
Tier 1 capital	0.173	0.186
Total capital	0.178	0.191
Tier 1 leverage capital ratio, actual	0.068	0.067
State Street Bank | Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 13,033	$ 13,033
Retained earnings	15,407	16,975
Accumulated other comprehensive income (loss)	(2,756)	(3,428)
Treasury stock, at cost	0	0
Total	25,684	26,580
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,096)	(8,288)
Other adjustments	(206)	(19)
Common equity tier 1 capital	17,382	18,273
Preferred stock	0	0
Tier 1 capital	17,382	18,273
Qualifying subordinated long-term debt	538	542
Allowance for credit losses	134	120
Total capital	18,054	18,935
Credit risk	114,662	104,184
Market risk	1,963	1,488
Total risk-weighted assets	116,625	105,672
Adjusted quarterly average assets	$ 256,408	$ 273,220
Common equity tier 1 capital	14.90%	17.30%
Tier 1 capital	0.149	0.173
Total capital	0.155	0.179
Tier 1 leverage capital ratio, actual	0.068	0.067