Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

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

The following tables set forth the postretirement health care plan status and amounts included in AOCI at December 31, the net periodic postretirement benefit cost of the plan for 2018 and 2017, and the change in the accumulated postretirement benefit obligation during 2018 and 2017.

TABLE 102: POSTRETIREMENT HEALTH CARE PLAN STATUS

	DECEMBER 31,
(In Millions)	2018		2017
Accumulated Postretirement Benefit Obligation at Measurement Date:
Retirees and Dependents	$	23.5	$	27.7
Actives Eligible for Benefits	4.6		6.7
Net Postretirement Benefit Obligation	$	28.1	$	34.4

The following tables set forth the status, amounts included in AOCI, and net periodic pension expense of the U.S. plan, non-U.S. plans, and supplemental plan for 2018, 2017, and 2016. Prior service costs are being amortized on a straight-line basis over 11 years for the U.S. plan and 9 years for the supplemental plan.

TABLE 94: EMPLOYEE BENEFIT PLAN STATUS

	U.S. PLAN						NON-U.S. PLANS						SUPPLEMENTAL PLAN
($ In Millions)	2018			2017			2018			2017			2018			2017
Accumulated Benefit Obligation	$	980.6		$	1,088.4		$	178.4		$	192.2		$	120.9		$	129.0
Projected Benefit Obligation	1,092.0			1,209.9			183.5			198.3			135.6			144.5
Plan Assets at Fair Value	1,380.1			1,506.4			166.7			178.7			—			—
Funded Status at December 31	$	288.1		$	296.5		$	(16.8	)	$	(19.6	)	$	(135.6	)	$	(144.5	)
Weighted-Average Assumptions:
Discount Rates	4.47		%	3.79		%	2.16		%	2.08		%	4.47		%	3.79		%
Rate of Increase in Compensation Level	4.39			4.39			1.75		%	1.75			4.39			4.39
Expected Long-Term Rate of Return on Assets	6.00			6.00			2.39			2.61			N/A			N/A

Amount Included in Accumulated Other Comprehensive Income

	U.S. PLAN						NON-U.S. PLANS				SUPPLEMENTAL PLAN
(In Millions)	2018			2017			2018		2017		2018		2017
Net Actuarial Loss	$	435.4		$	399.0		$	41.2	$	44.2	$	65.8	$	83.2
Prior Service Cost	(1.4		)	(1.8		)	3.6		2.5		0.4		0.6
Gross Amount in Accumulated Other Comprehensive Income	434.0			397.2			44.8		46.7		66.2		83.8
Income Tax Effect	108.5			151.6			6.0		5.3		16.4		31.9
Net Amount in Accumulated Other Comprehensive Income	$	325.5		$	245.6		$	38.8	$	41.4	$	49.8	$	51.9

	DECEMBER 31,
(In Millions)	2018			2017
Net Actuarial Loss / (Gain)	$	(6.5	)	$	3.9
Prior Service Cost	—			—
Gross Amount in Accumulated Other Comprehensive Income	(6.5		)	3.9
Income Tax Effect	(2.2		)	1.5
Net Amount in Accumulated Other Comprehensive Income	$	(4.3	)	$	2.4

Components of Company's Net Periodic Benefit Cost

	U.S. PLAN									NON-U.S. PLANS									SUPPLEMENTAL PLAN
($ In Millions)	2018			2017			2016			2018			2017			2016			2018			2017			2016
Service Cost	$	41.4		$	38.3		$	37.4		$	1.7		$	0.4		$	—		$	4.3		$	3.7		$	3.5
Interest Cost	44.3			45.9			45.8			4.0			4.0			4.7			5.3			5.2			5.1
Expected Return on Plan Assets	(88.2		)	(93.8		)	(94.4		)	(4.4		)	(4.5		)	(4.6		)	N/A			N/A			N/A
Settlement Expense	—			—			—			0.5			1.1			3.7			—			—			—
Amortization:
Net Loss	28.2			19.0			18.8			0.9			1.3			1.0			7.4			5.7			5.8
Prior Service Cost	(0.4		)	(0.4		)	(0.4		)	0.2			0.1			—			0.2			0.2			0.2
Net Periodic Pension Expense	$	25.3		$	9.0		$	7.2		$	2.9		$	2.4		$	4.8		$	17.2		$	14.8		$	14.6
Weighted-Average Assumptions:
Discount Rates	3.79		%	4.46		%	4.71		%	2.08		%	2.33		%	3.39		%	3.79		%	4.46		%	4.71		%
Rate of Increase in Compensation Level	4.39			4.39			4.25			1.75			1.75			N/A			4.39			4.39			4.25
Expected Long-Term Rate of Return on Assets	6.00			6.75			7.00			2.61			3.13			3.73			N/A			N/A			N/A

	FOR THE YEAR ENDED DECEMBER 31,
(In Millions)	2018		2017		2016
Service Cost	$	—	$	0.1	$	0.1
Interest Cost	1.3		1.4		1.5
Expected Return on Plan Assets	—		—		—
Amortization
Net Gain	—		—		—
Prior Service Benefit	—		—		—
Net Periodic Postretirement Expense	$	1.3	$	1.5	$	1.6

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

	U.S. PLAN						NON-U.S. PLANS						SUPPLEMENTAL PLAN
(In Millions)	2018			2017			2018			2017			2018			2017
Beginning Balance	$	1,209.9		$	1,062.7		$	198.3		$	155.9		$	144.5		$	121.1
Service Cost	41.4			38.3			1.7			0.4			4.3			3.7
Interest Cost	44.3			45.9			4.0			4.0			5.3			5.2
Employee Contributions	—			—			0.4			0.1			—			—
Plan Amendment	—			—			1.3			2.5			—			—
Actuarial (Gain) Loss	(112.4		)	142.6			(9.3		)	0.4			(9.7		)	21.5
Settlement	—			—			(2.7		)	(6.8		)	—			—
Acquisitions/Divestitures	—			—			—			27.0			—			—
Benefits Paid	(91.2		)	(79.6		)	(1.1		)	(3.0		)	(8.8		)	(7.0		)
Foreign Exchange Rate Changes	—			—			(9.1		)	17.8			—			—
Ending Balance	$	1,092.0		$	1,209.9		$	183.5		$	198.3		$	135.6		$	144.5

	FOR THE YEAR ENDED                       DECEMBER 31,
(In Millions)	2018			2017
Beginning Balance	$	34.4		$	34.1
Service Cost	—			0.1
Interest Cost	1.3			1.4
Actuarial Loss / (Gain)	(6.7		)	(0.2		)
Net Claims Paid	(6.3		)	(1.0		)
Medicare Subsidy	5.4			—
Ending Balance	$	28.1		$	34.4

Estimated Future Benefit Payments

(In Millions)	U.S. PLAN		NON-U.S. PLANS		SUPPLEMENTAL PLAN
2019	$	74.0	$	3.4	$	12.0
2020	76.8		3.8		11.5
2021	75.1		4.1		14.4
2022	73.4		3.9		16.2
2023	77.1		4.3		14.9
2024-2028	368.9		26.4		63.6

(In Millions)	TOTAL POSTRETIREMENT MEDICAL BENEFITS
2019	$	2.5
2020	2.5
2021	2.4
2022	2.3
2023	2.2
2024-2028	10.1

Change in Plan Assets

	U.S. PLAN						NON-U.S. PLANS
(In Millions)	2018			2017			2018			2017
Fair Value of Assets at Beginning of Period	$	1,506.4		$	1,393.5		$	178.7		$	139.3
Actual Return on Assets	(85.1		)	192.5			(2.3		)	12.4
Employer Contributions	50.0			—			2.6			3.0
Employee Contributions	—			—			0.4			0.1
Settlement	—			—			(2.7		)	(6.8		)
Acquisitions/Divestitures	—			—			—			18.5
Benefits Paid	(91.2		)	(79.6		)	(1.1		)	(3.0		)
Foreign Exchange Rate Changes	—			—			(8.9		)	15.2
Fair Value of Assets at End of Period	$	1,380.1		$	1,506.4		$	166.7		$	178.7

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. pension plan assets, by major asset category, and their level within the fair value hierarchy defined by GAAP as of December 31, 2018 and 2017.

TABLE 100: FAIR VALUE OF U.S. PENSION PLAN ASSETS

	December 31, 2018
(In Millions)	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Domestic Common Stock	$	36.3	$	—	$	—	$	36.3
Foreign Common Stock	—		—		—		—
U.S. Government Obligations	—		1,010.2		—		1,010.2
Northern Trust Mutual Fund	39.9		—		—		39.9
Exchange Traded Fund	0.1		—		—		0.1
Northern Trust Collective Trust Funds	—		226.5		—		226.5
Northern Trust Private Equity Funds	—		—		25.5		25.5
Northern Trust Hedge Funds	—		—		29.2		29.2
Cash and Other	12.4		—		—		12.4
Total Assets at Fair Value	$	88.7	$	1,236.7	$	54.7	$	1,380.1

	December 31, 2017
(In Millions)	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Domestic Common Stock	$	38.6	$	—	$	—	$	38.6
Foreign Common Stock	—		—		—		—
U.S. Government Obligations	—		1,072.0		—		1,072.0
Northern Trust Mutual Fund	44.5		—		—		44.5
Exchange Traded Fund	0.1		—		—		0.1
Northern Trust Collective Trust Funds	—		268.6		—		268.6
Northern Trust Private Equity Funds	—		—		29.3		29.3
Northern Trust Hedge Funds	—		—		44.6		44.6
Cash and Other	8.7		—		—		8.7
Total Assets at Fair Value	$	91.9	$	1,340.6	$	73.9	$	1,506.4

Changes in Level 3 U.S. Pension Plan Assets

The following table presents the changes in Level 3 assets for the years ended December 31, 2018 and 2017.

TABLE 101: CHANGE IN LEVEL 3 ASSETS

	PRIVATE EQUITY                       FUNDS						HEDGE FUNDS
(In Millions)	2018			2017			2018			2017
Fair Value at January 1	$	29.3		$	35.7		$	44.6		$	64.8
Actual Return on Plan Assets	(1.5		)	(5.4		)	(2.7		)	(3.1		)
Realized Gain	—			—			2.4			5.0
Purchases	0.3			0.8			—			—
Sales	(2.6		)	(1.8		)	(15.1		)	(22.1		)
Fair Value at December 31	$	25.5		$	29.3		$	29.2		$	44.6

Note: The return on plan assets represents the change in the unrealized gain (loss) on assets still held at December 31.

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