Regulatory Capital (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$ 25,612	$ 25,238
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
Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,266	$ 11,291
Retained earnings	25,612	25,238
Accumulated other comprehensive income (loss)	(2,698)	(1,133)
Treasury stock, at cost	(9,932)	(10,009)
Total	24,248	25,387
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,830)	(8,935)
Other adjustments	(392)	(505)
Common equity tier 1 capital	15,026	15,947
Preferred stock	1,976	1,976
Tier 1 capital	17,002	17,923
Qualifying subordinated long-term debt	1,586	1,588
Allowance for credit losses	0	0
Total capital	18,588	19,511
Credit risk	67,631	63,735
Operational risk	45,575	45,550
Market risk	1,763	2,113
Total risk-weighted assets	114,969	111,398
Adjusted quarterly average assets	$ 285,788	$ 293,567
Common equity tier 1 capital	13.10%	14.30%
Tier 1 capital	0.148	0.161
Total capital	0.162	0.175
Tier 1 leverage capital ratio, actual	0.059	0.061
Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 11,266	$ 11,291
Retained earnings	25,612	25,238
Accumulated other comprehensive income (loss)	(2,698)	(1,133)
Treasury stock, at cost	(9,932)	(10,009)
Total	24,248	25,387
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,830)	(8,935)
Other adjustments	(392)	(505)
Common equity tier 1 capital	15,026	15,947
Preferred stock	1,976	1,976
Tier 1 capital	17,002	17,923
Qualifying subordinated long-term debt	1,586	1,588
Allowance for credit losses	105	108
Total capital	18,693	19,619
Credit risk	124,962	109,554
Market risk	1,763	2,113
Total risk-weighted assets	126,725	111,667
Adjusted quarterly average assets	$ 285,788	$ 293,567
Common equity tier 1 capital	11.90%	14.30%
Tier 1 capital	0.134	0.161
Total capital	0.148	0.176
Tier 1 leverage capital ratio, actual	0.059	0.061
State Street Bank | Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 13,033	$ 13,047
Retained earnings	16,286	15,700
Accumulated other comprehensive income (loss)	(2,478)	(926)
Treasury stock, at cost	0	0
Total	26,841	27,821
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,564)	(8,667)
Other adjustments	(209)	(309)
Common equity tier 1 capital	18,068	18,845
Preferred stock	0	0
Tier 1 capital	18,068	18,845
Qualifying subordinated long-term debt	749	752
Allowance for credit losses	0	0
Total capital	18,817	19,597
Credit risk	60,693	57,405
Operational risk	42,863	42,813
Market risk	1,763	2,113
Total risk-weighted assets	105,319	102,331
Adjusted quarterly average assets	$ 282,685	$ 290,403
Common equity tier 1 capital	17.20%	18.40%
Tier 1 capital	0.172	0.184
Total capital	0.179	0.192
Tier 1 leverage capital ratio, actual	0.064	0.065
State Street Bank | Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	$ 13,033	$ 13,047
Retained earnings	16,286	15,700
Accumulated other comprehensive income (loss)	(2,478)	(926)
Treasury stock, at cost	0	0
Total	26,841	27,821
Goodwill and other intangible assets, net of associated deferred tax liabilities	(8,564)	(8,667)
Other adjustments	(209)	(309)
Common equity tier 1 capital	18,068	18,845
Preferred stock	0	0
Tier 1 capital	18,068	18,845
Qualifying subordinated long-term debt	749	752
Allowance for credit losses	105	108
Total capital	18,922	19,705
Credit risk	121,825	106,405
Market risk	1,763	2,113
Total risk-weighted assets	123,588	108,518
Adjusted quarterly average assets	$ 282,685	$ 290,403
Common equity tier 1 capital	14.60%	17.40%
Tier 1 capital	0.146	0.174
Total capital	0.153	0.182
Tier 1 leverage capital ratio, actual	0.064	0.065