Commitments and Contingent Liabilities (Narrative) (Details)		1 Months Ended	12 Months Ended	93 Months Ended
	Mar. 05, 2024 EUR (€)	May 31, 2024 exchange_offer shares	Dec. 31, 2015 trust	Sep. 30, 2025 USD ($) $ / shares shares	Dec. 31, 2024 USD ($)
Loss Contingencies [Line Items]
Minimum securities lending related collateral percentage				100.00%
Commitments and letters of credit				$ 321,232,600,000	$ 285,453,400,000
Repurchase agreement counterparty, amount at risk				0	0
Loss contingency accrual				$ 0
Common stock, convertible, conversion price				1.5223
Visa
Loss Contingencies [Line Items]
Escrow deposit				$ 5,100,000,000
Visa Class B-2 Shares
Loss Contingencies [Line Items]
Exchange offer program, shares received upon expiration (in shares) | shares		2,100,000
Carryover basis				0
Estimated value assuming conversion				$ 1,100,000,000
Visa Class C shares
Loss Contingencies [Line Items]
Exchange offer program, shares received upon expiration (in shares) | shares		819,500
Exchange offer program, number of exchange offers | exchange_offer		3
Exchange offer program, length of time between exchanges		12 months
Exchange offer program, claim reduction percentage		50.00%
Number of shares held (in shares) | shares				12,500
Equity securities				$ 17,100,000
Visa Class A | Visa
Loss Contingencies [Line Items]
Share price (in USD) | $ / shares				$ 341.38
Northern Trust Fiduciary Services (Guernsey) Limited | Subsidiaries
Loss Contingencies [Line Items]
Number of administrated trusts serving as trustee on | trust			2
Lower Limit
Loss Contingencies [Line Items]
Estimated loss				$ 0
Upper Limit
Loss Contingencies [Line Items]
Estimated loss				25,000,000
Indemnification Agreement
Loss Contingencies [Line Items]
Credit loss liability				0	0
Northern Trust Fiduciary Services (Guernsey) Limited
Loss Contingencies [Line Items]
Litigation settlement, amount awarded to other party | €	€ 187,500
Securities Lent with Indemnification
Loss Contingencies [Line Items]
Commitments and letters of credit				$ 167,606,500,000	$ 144,543,700,000