Regulatory Capital (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$ 29,582	$ 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
Capital ratio: required total capital	0.040	0.040
Leverage ratio minimum	0.05
Capital conservation buffer, capital conserved, minimum	0.025
Stress capital buffer, minimum	2.50%
Banking regulation, global systemically important bank (G-SIB) surcharge	0.010
Countercyclical capital buffer	0
Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,226	$ 11,245
Retained earnings	29,582	27,957
Accumulated other comprehensive income (loss)	(2,100)	(2,354)
Treasury stock, at cost		(15,025)
Total	22,510	21,823
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,320)	(8,470)
Other adjustments	(391)	(382)
Common equity tier 1 capital	13,799	12,971
Preferred stock	2,816	1,976
Tier 1 capital	16,615	14,947
Qualifying subordinated long-term debt	1,861	1,870
Adjusted allowance for credit losses	0	0
Total capital	18,476	16,817
Credit risk	63,252	61,210
Operational risk	49,350	43,768
Market risk	2,000	2,475
Total risk-weighted assets	114,602	107,453
Adjusted quarterly average assets	$ 318,470	$ 269,807
Common equity tier 1 capital	12.00%	12.10%
Tier 1 capital	0.145	0.139
Total capital	0.161	0.157
Tier 1 leverage	0.052	0.055
Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,226	$ 11,245
Retained earnings	29,582	27,957
Accumulated other comprehensive income (loss)	(2,100)	(2,354)
Total	22,510	21,823
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,320)	(8,470)
Other adjustments	(391)	(382)
Common equity tier 1 capital	13,799	12,971
Preferred stock	2,816	1,976
Tier 1 capital	16,615	14,947
Qualifying subordinated long-term debt	1,861	1,870
Adjusted allowance for credit losses	183	150
Total capital	18,659	16,967
Credit risk	124,281	109,228
Market risk	2,000	2,475
Total risk-weighted assets	126,281	111,703
Adjusted quarterly average assets	$ 318,470	$ 269,807
Common equity tier 1 capital	10.90%	11.60%
Tier 1 capital	0.132	0.134
Total capital	0.148	0.152
Tier 1 leverage	0.052	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	15,977	14,454
Accumulated other comprehensive income (loss)	(1,805)	(2,097)
Treasury stock, at cost	0	0
Total	27,505	25,390
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,054)	(8,208)
Other adjustments	(278)	(298)
Common equity tier 1 capital	19,173	16,884
Preferred stock	0	0
Tier 1 capital	19,173	16,884
Qualifying subordinated long-term debt	530	536
Adjusted allowance for credit losses	0	0
Total capital	19,703	17,420
Credit risk	57,883	54,942
Operational risk	47,538	42,297
Market risk	2,000	2,475
Total risk-weighted assets	107,421	99,714
Adjusted quarterly average assets	$ 314,754	$ 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	0.061	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	15,977	14,454
Accumulated other comprehensive income (loss)	(1,805)	(2,097)
Treasury stock, at cost	0	0
Total	27,505	25,390
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,054)	(8,208)
Other adjustments	(278)	(298)
Common equity tier 1 capital	19,173	16,884
Preferred stock	0	0
Tier 1 capital	19,173	16,884
Qualifying subordinated long-term debt	530	536
Adjusted allowance for credit losses	183	150
Total capital	19,886	17,570
Credit risk	121,785	107,067
Market risk	2,000	2,475
Total risk-weighted assets	123,785	109,542
Adjusted quarterly average assets	$ 314,754	$ 266,818
Common equity tier 1 capital	15.50%	15.40%
Tier 1 capital	0.155	0.154
Total capital	0.161	0.160
Tier 1 leverage	0.061	0.063