Regulatory Capital (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$ 27,808	$ 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	$ 11,233	$ 11,234
Retained earnings	27,808	27,028
Accumulated other comprehensive income (loss)	(3,258)	(3,711)
Treasury stock, at cost	(13,555)	(11,336)
Total	22,228	23,215
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,480)	(8,545)
Other adjustments	(252)	(123)
Common equity tier 1 capital	13,496	14,547
Preferred stock	1,976	1,976
Tier 1 capital	15,472	16,523
Qualifying subordinated long-term debt	1,375	1,376
Allowance for credit losses	0	0
Other adjustments	7	0
Total capital	16,854	17,899
Credit risk	62,196	61,108
Operational risk	42,562	42,763
Market risk	1,763	1,488
Total risk-weighted assets	106,521	105,359
Adjusted quarterly average assets	$ 266,240	$ 275,678
Common equity tier 1 capital	12.70%	13.80%
Tier 1 capital	0.145	0.157
Total capital	0.158	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	$ 11,233	$ 11,234
Retained earnings	27,808	27,028
Accumulated other comprehensive income (loss)	(3,258)	(3,711)
Treasury stock, at cost	(13,555)	(11,336)
Total	22,228	23,215
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,480)	(8,545)
Other adjustments	(252)	(123)
Common equity tier 1 capital	13,496	14,547
Preferred stock	1,976	1,976
Tier 1 capital	15,472	16,523
Qualifying subordinated long-term debt	1,375	1,376
Allowance for credit losses	135	120
Other adjustments	0	0
Total capital	16,982	18,019
Credit risk	112,259	105,739
Market risk	1,763	1,488
Total risk-weighted assets	114,022	107,227
Adjusted quarterly average assets	$ 266,240	$ 275,678
Common equity tier 1 capital	11.80%	13.60%
Tier 1 capital	0.136	0.154
Total capital	0.149	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	15,976	16,975
Accumulated other comprehensive income (loss)	(2,992)	(3,428)
Treasury stock, at cost	0	0
Total	26,017	26,580
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,219)	(8,288)
Other adjustments	(154)	(19)
Common equity tier 1 capital	17,644	18,273
Preferred stock	0	0
Tier 1 capital	17,644	18,273
Qualifying subordinated long-term debt	539	542
Allowance for credit losses	0	0
Other adjustments	7	0
Total capital	18,190	18,815
Credit risk	56,456	54,675
Operational risk	42,202	42,325
Market risk	1,763	1,488
Total risk-weighted assets	100,421	98,488
Adjusted quarterly average assets	$ 263,448	$ 273,220
Common equity tier 1 capital	17.60%	18.60%
Tier 1 capital	0.176	0.186
Total capital	0.181	0.191
Tier 1 leverage capital ratio, actual	0.067	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	15,976	16,975
Accumulated other comprehensive income (loss)	(2,992)	(3,428)
Treasury stock, at cost	0	0
Total	26,017	26,580
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,219)	(8,288)
Other adjustments	(154)	(19)
Common equity tier 1 capital	17,644	18,273
Preferred stock	0	0
Tier 1 capital	17,644	18,273
Qualifying subordinated long-term debt	539	542
Allowance for credit losses	135	120
Other adjustments	0	0
Total capital	18,318	18,935
Credit risk	110,887	104,184
Market risk	1,763	1,488
Total risk-weighted assets	112,650	105,672
Adjusted quarterly average assets	$ 263,448	$ 273,220
Common equity tier 1 capital	15.70%	17.30%
Tier 1 capital	0.157	0.173
Total capital	0.163	0.179
Tier 1 leverage capital ratio, actual	0.067	0.067