Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Plan Status of U.S. Plan, Non-U.S. Plans and Supplemental Plan

The following tables set forth the status, amounts included in AOCI, and net periodic pension expense of the U.S. Qualified Plan, Non-U.S. Pension Plans, and U.S. Non-Qualified Plan for 2020, 2019, and 2018. Prior service costs are being amortized on a straight-line basis over 11 years for the U.S. Qualified Plan and 10 years for the U.S. Non-Qualified Plan of which approximately one year was remaining as of December 31, 2020 for both the U.S. Qualified Plan and the U.S. Non-Qualified Plan.

TABLE 110: EMPLOYEE BENEFIT PLAN STATUS

	U.S. QUALIFIED PLAN						NON-U.S. PENSION PLANS						U.S. NON-QUALIFIED PLAN
($ In Millions)	2020			2019			2020			2019			2020			2019
Accumulated Benefit Obligation	$	1,312.9		$	1,181.9		$	228.5		$	204.7		$	139.8		$	131.5
Projected Benefit Obligation	$	1,470.6		$	1,323.4		$	236.1		$	211.1		$	162.3		$	149.2
Plan Assets at Fair Value	1,793.7			1,601.2			211.5			190.1			—			—
Funded Status at December 31	$	323.1		$	277.8		$	(24.6)		$	(21.0)		$	(162.3)		$	(149.2)
Weighted-Average Assumptions:
Discount Rates	2.75		%	3.37		%	0.93		%	1.40		%	2.45		%	3.37		%
Rate of Increase in Compensation Level	4.97			4.97			1.50			1.50			4.97			4.97
Expected Long-Term Rate of Return on Assets	5.25			5.25			1.28			1.72			N/A			N/A

The following tables set forth the postretirement health care plan status and amounts included in AOCI at December 31, 2020 and 2019, the net periodic postretirement benefit cost of the plan for 2020 and 2019, and the change in the accumulated postretirement benefit obligation during 2020 and 2019.

TABLE 117: POSTRETIREMENT HEALTH CARE PLAN STATUS

	DECEMBER 31,
(In Millions)	2020		2019
Accumulated Postretirement Benefit Obligation at Measurement Date:
Retirees and Dependents	$	13.2	$	25.2
Actives Eligible for Benefits	2.5		3.6
Net Postretirement Benefit Obligation	$	15.7	$	28.8

Amount Included in Accumulated Other Comprehensive Income

	U.S. QUALIFIED PLAN				NON-U.S. PENSION PLANS				U.S. NON-QUALIFIED PLAN
(In Millions)	2020		2019		2020		2019		2020		2019
Net Actuarial Loss	$	332.4	$	426.7	$	49.0	$	46.5	$	96.3	$	82.5
Prior Service (Benefit) Cost	(0.6)		(1.0)		2.2		3.0		0.1		0.2
Gross Amount in Accumulated Other Comprehensive Income	331.8		425.7		51.2		49.5		96.4		82.7
Income Tax Effect	82.1		105.7		6.4		6.2		23.9		20.4
Net Amount in Accumulated Other Comprehensive Income	$	249.7	$	320.0	$	44.8	$	43.3	$	72.5	$	62.3

	DECEMBER 31,
(In Millions)	2020		2019
Net Actuarial (Gain) Loss	$	(4.9)	$	(5.4)
Prior Service Cost	(12.4)		—
Gross Amount in Accumulated Other Comprehensive Income	(17.3)		(5.4)
Income Tax Effect	(4.3)		(1.4)
Net Amount in Accumulated Other Comprehensive Income	$	(13.0)	$	(4.0)

Components of Company's Net Periodic Benefit Cost

	U.S. QUALIFIED PLAN									NON-U.S. PENSION PLANS									U.S. NON-QUALIFIED PLAN
($ In Millions)	2020			2019			2018			2020			2019			2018			2020			2019			2018
Service Cost	$	47.4		$	41.6		$	41.4		$	1.9		$	2.0		$	1.7		$	4.6		$	4.1		$	4.3
Interest Cost	43.3			47.2			44.3			2.9			3.9			4.0			4.8			5.8			5.3
Expected Return on Plan Assets	(76.8)			(86.9)			(88.2)			(3.1)			(4.4)			(4.4)			—			—			N/A
Settlement Expense	—			—			—			0.8			—			0.5			—			—			—
Amortization:
Net Actuarial Loss	35.0			17.2			28.2			0.8			0.6			0.9			7.0			5.6			7.4
Prior Service (Benefit) Cost	(0.4)			(0.4)			(0.4)			0.4			0.3			0.2			0.2			0.2			0.2
Net Periodic Pension Expense	$	48.5		$	18.7		$	25.3		$	3.7		$	2.4		$	2.9		$	16.6		$	15.7		$	17.2
Weighted-Average Assumptions:
Discount Rates	3.37		%	4.47		%	3.79		%	1.40		%	2.16		%	2.08		%	3.37		%	4.47		%	3.79		%
Rate of Increase in Compensation Level	4.97			4.39			4.39			1.50			1.75			1.75			4.97			4.39			4.39
Expected Long-Term Rate of Return on Assets	5.25			6.00			6.00			1.72			2.39			2.61			N/A			N/A			N/A

	FOR THE YEAR ENDED DECEMBER 31,
(In Millions)	2020		2019		2018
Service Cost	$	—	$	—	$	—
Interest Cost	0.7		1.2		1.3
Expected Return on Plan Assets	—		—		—
Amortization
Net Gain	(0.6)		(1.1)		—
Prior Service Benefit	(0.3)		—		—
Net Periodic Postretirement Expense	$	(0.2)	$	0.1	$	1.3

Change in Benefit Obligation, Postretirement Health Care, and in Accumulated Postretirement Benefit Obligation

	U.S. QUALIFIED PLAN				NON-U.S. PENSION PLANS				U.S. NON-QUALIFIED PLAN
(In Millions)	2020		2019		2020		2019		2020		2019
Beginning Balance	$	1,323.4	$	1,092.0	$	211.1	$	183.5	$	149.2	$	135.6
Service Cost	47.4		41.6		1.9		2.0		4.6		4.1
Interest Cost	43.3		47.2		2.9		3.9		4.8		5.8
Employee Contributions	—		—		0.6		0.6		—		—
Plan Amendment	—		—		(0.5)		(0.4)		—		—
Actuarial Loss (Gain)	136.5		213.3		19.1		20.9		20.4		22.0
Settlement	—		—		(5.4)		—		—		—
Benefits Paid	(80.0)		(70.7)		(4.1)		(3.6)		(16.7)		(18.3)
Foreign Exchange Rate Changes	—		—		10.5		4.2		—		—
Ending Balance	$	1,470.6	$	1,323.4	$	236.1	$	211.1	$	162.3	$	149.2

	FOR THE YEAR ENDED DECEMBER 31,
(In Millions)	2020		2019
Beginning Balance	$	28.8	$	28.1
Service Cost	—		—
Interest Cost	0.7		1.2
Plan Amendment	(12.7)		—
Actuarial Loss (Gain)	(0.1)		0.2
Net Claims Paid	(1.0)		(0.7)
Ending Balance	$	15.7	$	28.8

Estimated Future Benefit Payments

(In Millions)	U.S. QUALIFIED PLAN		NON-U.S.PENSION PLANS		U.S. NON-QUALIFIED PLAN
2021	$	86.8	$	4.4	$	18.0
2022	88.9		4.3		20.0
2023	96.3		4.8		18.2
2024	96.4		5.0		11.6
2025	98.6		5.0		12.7
2026-2030	495.5		32.4		62.0

(In Millions)	TOTAL POSTRETIREMENT MEDICAL BENEFITS
2021	$	1.7
2022	1.5
2023	1.4
2024	1.3
2025	1.2
2026-2030	5.1

Change in Plan Assets

	U.S. QUALIFIED PLAN				NON-U.S PENSION PLANS
(In Millions)	2020		2019		2020		2019
Fair Value of Assets at Beginning of Period	$	1,601.2	$	1,380.1	$	190.1	$	166.7
Actual Return on Assets	272.5		291.8		17.9		18.6
Employer Contributions	—		—		5.0		3.1
Employee Contributions	—		—		0.6		0.6
Settlement	—		—		(5.4)		—
Benefits Paid	(80.0)		(70.7)		(4.1)		(3.6)
Foreign Exchange Rate Changes	—		—		7.4		4.7
Fair Value of Assets at End of Period	$	1,793.7	$	1,601.2	$	211.5	$	190.1

Fair Values of U.S. Pension Plan Assets by Major Asset Category, and their Level within Fair Value Hierarchy

The following table presents the fair values of Northern Trust’s U.S. Qualified Plan assets, by major asset category, and their level within the fair value hierarchy defined by GAAP as of December 31, 2020 and 2019.

TABLE 116: FAIR VALUE OF U.S. QUALIFIED PLAN ASSETS

	DECEMBER 31, 2020
(In Millions)	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Domestic Common Stock	$	13.5	$	—	$	—	$	13.5
Domestic Corporate Bonds	—		314.4		—		314.4
Foreign Corporate Bonds	—		43.6		—		43.6
U.S. Government Obligations	2.9		113.1		—		116.0
Non-U.S. Government Obligations	—		22.9		—		22.9
Domestic Municipal and Provincial Bonds	—		22.4		—		22.4
Foreign Municipal and Provincial Bonds	—		0.3		—		0.3
Collective Trust Funds	—		985.5		—		985.5
Mutual Funds	167.0		—		—		167.0
Cash and Other	7.5		—		—		7.5
Total Assets at Fair Value in the Fair Value Hierarchy	$	190.9	$	1,502.2	$	—	$	1,693.1
Assets Valued at NAV per share
Northern Trust Private Equity Funds							20.3
Northern Trust Hedge Fund							34.2
Real Estate Funds							46.1
Total Assets at Fair Value							$	1,793.7

	DECEMBER 31, 2019
(In Millions)	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Domestic Common Stock	$	12.3	$	—	$	—	$	12.3
Domestic Corporate Bonds	—		254.6		—		254.6
Foreign Corporate Bonds	—		45.0		—		45.0
U.S. Government Obligations	—		168.3		—		168.3
Non-U.S. Government Obligations	—		18.8		—		18.8
Domestic Municipal and Provincial Bonds	—		23.1		—		23.1
Foreign Municipal and Provincial Bonds	—		0.3		—		0.3
Collective Trust Funds	—		866.6		—		866.6
Mutual Funds	112.8		—		—		112.8
Cash and Other	2.6		—		—		2.6
Total Assets at Fair Value in the Fair Value Hierarchy	$	127.7	$	1,376.7	$	—	$	1,504.4
Assets Valued at NAV per share
Northern Trust Private Equity Funds							20.3
Northern Trust Hedge Fund							30.2
Real Estate Funds							46.3
Total Assets at Fair Value							$	1,601.2

Changes in Level 3 U.S. Pension Plan Assets