Commitments and Contingent Liabilities (Narrative) (Details)		1 Months Ended	3 Months Ended	12 Months Ended	99 Months Ended
	Mar. 05, 2024 EUR (€)	May 31, 2026	Jun. 30, 2026 USD ($) $ / shares shares	Dec. 31, 2015 trust	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)
Loss Contingencies [Line Items]
Commitments and letters of credit			$ 358,455,500,000			$ 349,426,200,000
Repurchase agreement counterparty, amount at risk			0			0
Loss contingency accrual			$ 0
Common stock, convertible, conversion price			1.4953
Visa Class B-3 Shares
Loss Contingencies [Line Items]
Exchange offer program, percentage of new shares received		50.00%
Carryover basis			$ 0
Estimated value assuming conversion			$ 529,700,000
Visa Class C shares
Loss Contingencies [Line Items]
Exchange offer program, percentage of new shares received		50.00%
Number of shares held (in shares) | shares			270,100
Equity securities			$ 370,700,000
Number of shares sold (in shares) | shares			129,700
Sale of shares realized gain			$ 169,300,000
Visa
Loss Contingencies [Line Items]
Escrow deposit					$ 6,000,000,000.0
Visa | Visa Class A
Loss Contingencies [Line Items]
Share price (in USD) | $ / shares			$ 343.09
Subsidiaries | Northern Trust Fiduciary Services (Guernsey) Limited
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			10,000,000
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			$ 194,000,100,000			$ 170,738,800,000