Regulatory Capital Requirements (Tables)

12 Months Ended

Dec. 31, 2025

Regulatory Capital Requirements Abstract [Abstract]

Schedule of Risk-Based Capital Amounts and Ratios for Northern Trust on Consolidated Basis and for Bank

The following table provides capital ratios for the Corporation and the Bank determined by Basel III phased in requirements.

TABLE 121: RISK-BASED AND LEVERAGE CAPITAL AMOUNTS AND RATIOS

	DECEMBER 31, 2025								DECEMBER 31, 2024
($ In Millions)	STANDARDIZED APPROACH				ADVANCED APPROACH				STANDARDIZED APPROACH				ADVANCED APPROACH
	BALANCE		RATIO		BALANCE		RATIO		BALANCE		RATIO		BALANCE		RATIO
Common Equity Tier 1 Capital
Northern Trust Corporation	$	11,192.5	12.6	%	$	11,192.5	15.0	%	$	11,038.2	12.4	%	$	11,038.2	14.5	%
The Northern Trust Company	10,582.2		12.1		10,582.2		14.6		9,983.8		11.4		9,983.8		13.6
Minimum to qualify as well-capitalized:
Northern Trust Corporation	N/A		N/A		N/A		N/A		N/A		N/A		N/A		N/A
The Northern Trust Company	5,700.4		6.5		4,718.7		6.5		5,703.2		6.5		4,789.1		6.5
Tier 1 Capital
Northern Trust Corporation	12,008.5		13.5		12,008.5		16.0		11,870.2		13.3		11,870.2		15.6
The Northern Trust Company	10,582.2		12.1		10,582.2		14.6		9,983.8		11.4		9,983.8		13.6
Minimum to qualify as well-capitalized:
Northern Trust Corporation	5,340.9		6.0		4,490.6		6.0		5,336.4		6.0		4,555.3		6.0
The Northern Trust Company	7,015.9		8.0		5,807.6		8.0		7,019.4		8.0		5,894.2		8.0
Total Capital
Northern Trust Corporation	14,304.2		16.1		14,105.8		18.8		13,423.2		15.1		13,217.3		17.4
The Northern Trust Company	12,530.5		14.3		12,332.2		17.0		11,241.7		12.8		11,035.8		15.0
Minimum to qualify as well-capitalized:
Northern Trust Corporation	8,901.5		10.0		7,484.4		10.0		8,894.0		10.0		7,592.1		10.0
The Northern Trust Company	8,769.8		10.0		7,259.5		10.0		8,774.2		10.0		7,367.8		10.0
Tier 1 Leverage
Northern Trust Corporation	12,008.5		7.8		12,008.5		7.8		11,870.2		8.1		11,870.2		8.1
The Northern Trust Company	10,582.2		6.9		10,582.2		6.9		9,983.8		6.9		9,983.8		6.9
Minimum to qualify as well-capitalized:
Northern Trust Corporation	N/A		N/A		N/A		N/A		N/A		N/A		N/A		N/A
The Northern Trust Company	7,676.0		5.0		7,676.0		5.0		7,262.3		5.0		7,262.3		5.0
Supplementary Leverage
Northern Trust Corporation	N/A		N/A		12,008.5		8.7		N/A		N/A		11,870.2		8.9
The Northern Trust Company	N/A		N/A		10,582.2		7.7		N/A		N/A		9,983.8		7.5
Minimum to qualify as well-capitalized:
Northern Trust Corporation	N/A		N/A		N/A		N/A		N/A		N/A		N/A		N/A
The Northern Trust Company	N/A		N/A		4,126.8		3.0		N/A		N/A		3,974.3		3.0