Consolidated Statements of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income		$ 1,736.9	$ 2,031.1	$ 1,107.3
Adjustments to Reconcile Net Income to Net Cash Provided by (Used in) Operating Activities
Investment Security Losses, net		0.0	189.3	169.5
Amortization and Accretion of Securities and Unearned Income, net		(67.8)	(35.1)	3.0
Provision for Credit Losses		(7.5)	(3.0)	24.5
Depreciation and Amortization		779.1	716.8	634.6
Change in Accrued Income Taxes		(104.4)	183.5	(44.4)
Pension Plan Contributions		(142.1)	(212.0)	(20.4)
Deferred Income Tax Provision		194.5	20.7	(48.2)
Change in Receivables		(42.6)	(6.1)	12.0
Change in Interest Payable		(24.8)	(41.9)	85.8
Change in Collateral With Derivative Counterparties, net		2,885.7	(3,287.7)	(72.6)
Other Operating Activities, net		326.5	(41.6)	774.5
Net Cash Provided by (Used in) Operating Activities		5,533.5	(486.0)	2,625.6
CASH FLOWS FROM INVESTING ACTIVITIES
Change in Federal Funds Sold and Securities Purchased under Agreements to Resell		(2,175.6)	276.6	317.4
Change in Interest-Bearing Deposits with Banks		277.2	(121.0)	28.5
Net Change in Federal Reserve and Other Central Bank Deposits		(13,263.6)	(5,255.3)	6,205.9
Purchases of Held to Maturity Debt Securities		(33,137.2)	(26,524.6)	(32,773.9)
Proceeds from the Maturity and Redemption of Held to Maturity Debt Securities		32,803.6	30,073.9	32,123.0
Purchases of Available for Sale Debt Securities		(9,428.8)	(13,010.0)	(7,320.2)
Proceeds from the Maturity and Sales of Available for Sale Debt Securities		4,982.1	6,983.0	11,614.8
Change in Loans		1,520.8	4,165.7	(4,702.1)
Purchases of Buildings and Equipment		(74.0)	(101.5)	(116.5)
Purchases and Development of Computer Software		(700.2)	(644.0)	(559.3)
Proceeds from the sale of Visa Shares		12.1	800.6	0.0
Other Investing Activities, net		(986.3)	793.1	(33.5)
Net Cash (Used in) Provided by Investing Activities		(20,169.9)	(2,563.5)	4,784.1
CASH FLOWS FROM FINANCING ACTIVITIES
Change in Deposits		16,809.1	6,330.8	(8,478.4)
Change in Federal Funds Purchased		(18.4)	(885.9)	1,148.6
Change in Securities Sold under Agreements to Repurchase		(169.8)	(322.7)	217.5
Change in Short-Term Other Borrowings		566.8	(103.8)	(1,059.1)
Proceeds from Long-Term Debt		750.0	0.0	2,000.0
Repayments of Long-Term Debt		(1,350.0)	0.0	0.0
Proceeds from Senior Notes		499.8	0.0	0.0
Treasury Stock Purchased		(1,273.5)	(937.8)	(347.5)
Net Proceeds from Stock Options		6.4	9.4	2.3
Cash Dividends Paid on Common Stock		(591.6)	(602.3)	(621.5)
Cash Dividends Paid on Preferred Stock		(41.8)	(41.8)	(41.8)
Other Financing Activities, net		(11.1)	(6.4)	(2.7)
Net Cash Provided by (Used in) Financing Activities		15,175.9	3,439.5	(7,182.6)
Effect of Foreign Currency Exchange Rates on Cash		656.4	(504.3)	(89.8)
Change in Cash and Due from Banks		1,195.9	(114.3)	137.3
Cash and Due from Banks at Beginning of Period		4,677.2	4,791.5	4,654.2
Cash and Due from Banks at End of Period		5,873.1	4,677.2	4,791.5
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest Paid		6,223.7	7,610.3	5,285.5
Income Taxes Paid	[1]	426.8	268.6	362.5
Transfers from Loans to OREO		0.0	0.0	0.2
Reclassification of certain cash collateral received from Other Operating Activities to Deposits	[2]	$ 0.0	$ 1,157.2	$ 0.0

[1] See Note 20, “Income Taxes” for additional information.

[2] Beginning January 1, 2024, Northern Trust reclassified certain cash collateral received from Other Liabilities to Deposits on the consolidated statement of financial condition. Prior periods have not been restated.