Regulatory Capital Requirements (Tables)

12 Months Ended

Dec. 31, 2018

Banking and Thrift [Abstract]

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

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

TABLE 126: RISK-BASED AND LEVERAGE CAPITAL AMOUNTS AND RATIOS

	December 31, 2018								December 31, 2017
($ In Millions)	ADVANCED APPROACH				STANDARDIZED APPROACH				ADVANCED APPROACH				STANDARDIZED APPROACH
	BALANCE		RATIO		BALANCE		RATIO		BALANCE		RATIO		BALANCE		RATIO
Common Equity Tier 1
Northern Trust Corporation	$	8,729.8	13.7	%	$	8,729.8	12.9	%	$	8,626.3	13.5	%	$	8,626.3	12.6	%
The Northern Trust Company	8,722.5		14.1		8,722.5		13.1		8,517.8		13.7		8,517.8		12.6
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	4,007.4		6.5		4,335.9		6.5		4,032.7		6.5		4,406.8		6.5
Tier 1
Northern Trust Corporation	9,596.7		15.0		9,596.7		14.1		9,473.4		14.8		9,473.4		13.8
The Northern Trust Company	8,722.5		14.1		8,722.5		13.1		8,517.8		13.7		8,517.8		12.6
Minimum to qualify as well-capitalized:
Northern Trust Corporation	3,834.9		6.0		4,070.0		6.0		3,841.1		6.0		4,117.0		6.0
The Northern Trust Company	4,932.2		8.0		5,336.4		8.0		4,963.3		8.0		5,423.8		8.0
Total
Northern Trust Corporation	10,803.8		16.9		10,942.0		16.1		10,707.4		16.7		10,861.2		15.8
The Northern Trust Company	9,732.5		15.8		9,870.7		14.8		9,527.8		15.4		9,681.6		14.3
Minimum to qualify as well-capitalized:
Northern Trust Corporation	6,391.5		10.0		6,783.7		10.0		6,401.9		10.0		6,861.6		10.0
The Northern Trust Company	6,165.3		10.0		6,670.6		10.0		6,204.2		10.0		6,779.7		10.0
Tier 1 Leverage
Northern Trust Corporation	9,596.7		8.0		9,596.7		8.0		9,473.4		7.8		9,473.4		7.8
The Northern Trust Company	8,722.5		7.3		8,722.5		7.3		8,517.8		7.0		8,517.8		7.0
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	5,998.6		5.0		5,998.6		5.0		6,057.9		5.0		6,057.9		5.0
Supplementary Leverage (1)
Northern Trust Corporation	9,596.7		7.0		N/A		N/A		9,473.4		6.8		N/A		N/A
The Northern Trust Company	8,722.5		6.4		N/A		N/A		8,517.8		6.1		N/A		N/A
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	4,077.2		3.0		N/A		N/A		N/A		N/A		N/A		N/A

(1) Effective January 1, 2018, a minimum supplementary leverage ratio of 3 percent became applicable.