Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2015

Defined Benefit Plan Disclosure [Line Items]



	U.S. PLAN						NON-U.S. PLANS
(In Millions)	2015			2014			2015			2014
Fair Value of Assets at Beginning of Period	$	1,440.8		$	1,342.1		$	157.6		$	148.5
Actual Return on Assets	(25.0		)	157.1			1.3			22.2
Employer Contributions	—			—			4.6			4.8
Benefits Paid	(73.8		)	(58.4		)	(9.4		)	(6.6		)
Foreign Exchange Rate Changes	—			—			(9.8		)	(11.3		)

Fair Value of Assets at End of Period	$	1,342.0		$	1,440.8		$	144.3		$	157.6

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, 2015 and 2014.

TABLE 94: FAIR VALUE OF U.S. PENSION PLAN ASSETS



	December 31, 2015
(In Millions)	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Common Stock
U.S.	$	45.4	$	—	$	—	$	45.4
Canada	0.3		—		—		0.3
Fixed Income – U.S. Government	—		135.7		—		135.7
Other Investments
Mutual Funds:
Global Large Cap Blend	64.3		—		—		64.3
Exchange Traded Fund:
Domestic Large Cap Core	0.5		—		—		0.5
Collective Trust Funds:
Foreign Large Cap Blend	—		113.0		—		113.0
Foreign Small Cap Blend	—		37.1		—		37.1
Domestic Small Cap Value	—		104.9		—		104.9
Domestic Small Cap Growth	—		15.0		—		15.0
Domestic Large Cap Growth	—		36.6		—		36.6
Domestic Large Cap Minimum Volatility	—		82.4		—		82.4
Short-Term Investment	—		5.5		—		5.5
Global Real Estate Blend	—		67.0		—		67.0
Domestic Long-Term Bond	—		464.3		—		464.3
Emerging Market Large Cap Blend	—		59.1		—		59.1
Private Equity Funds	—		—		47.5		47.5
Hedge Funds	—		—		63.4		63.4

Total Assets at Fair Value	$	110.5	$	1,120.6	$	110.9	$	1,342.0



	December 31, 2014
(In Millions)	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Common Stock
U.S.	$	14.8	$	—	$	—	$	14.8
Fixed Income – U.S. Government	—		159.5		—		159.5
Other Investments
Mutual Funds:
Global Large Cap Blend	69.6		—		—		69.6
Collective Trust Funds:
Foreign Large Cap Blend	—		105.4		—		105.4
Foreign Small Cap Blend	—		37.2		—		37.2
Domestic Large Cap Blend	—		196.7		—		196.7
Domestic Small Cap Value	—		26.5		—		26.5
Domestic Mid Cap Value	—		14.4		—		14.4
Domestic Small Cap Growth	—		21.2		—		21.2
Domestic Mid Cap Growth	—		15.2		—		15.2
Short-Term Investment	—		3.4		—		3.4
Global Real Estate Blend	—		73.8		—		73.8
Domestic Long-Term Bond	—		508.0		—		508.0
Emerging Market Large Cap Blend	—		68.2		—		68.2
Private Equity Funds	—		—		49.0		49.0
Hedge Funds	—		—		68.6		68.6
Cash and Other	9.3		—		—		9.3

Total Assets at Fair Value	$	93.7	$	1,229.5	$	117.6	$	1,440.8

Health Care Cost Trend Rate Sensitivity Analysis

For example, increasing or decreasing the assumed health care trend rate by one percentage point in each year would have the following effect.

TABLE 101: HEALTH CARE COST TREND RATE ASSUMPTION



(In Millions)	1–PERCENTAGE POINT INCREASE		1–PERCENTAGE POINT DECREASE
Effect on Postretirement Benefit Obligation	$	0.9	$	(0.8	)
Effect on Total Service and Interest Cost Components	—		—

Pension Plans, Defined Benefit

Defined Benefit Plan Disclosure [Line Items]

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. plan, non-U.S. plans, and supplemental plan for 2015, 2014, and 2013. 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 88: EMPLOYEE BENEFIT PLAN STATUS



	U.S. PLAN						NON-U.S. PLANS						SUPPLEMENTAL PLAN
($ In Millions)	2015			2014			2015			2014			2015			2014
Accumulated Benefit Obligation	$	903.4		$	974.8		$	156.5		$	184.6		$	102.1		$	109.2

Projected Benefit Obligation	1,006.5			1,091.5			156.5			184.6			113.9			123.0
Plan Assets at Fair Value	1,342.0			1,440.8			144.3			157.6			—			—

Funded Status at December 31	$	335.5		$	349.3		$	(12.2	)	$	(27.0	)	$	(113.9	)	$	(123.0	)
Weighted-Average Assumptions:
Discount Rates	4.71		%	4.25		%	3.39		%	3.20		%	4.71		%	4.25		%
Rate of Increase in Compensation Level	4.25			4.25			N/A			N/A			4.25			4.25
Expected Long-Term Rate of Return on Assets	7.00			7.25			3.73			4.00			N/A			N/A

Amount Included in Accumulated Other Comprehensive Income



	U.S. PLAN						NON-U.S. PLANS				SUPPLEMENTAL PLAN
(In Millions)	2015			2014			2015		2014		2015		2014
Net Actuarial Loss	$	381.0		$	382.9		$	51.6	$	60.5	$	66.1	$	81.5
Prior Service Cost	(2.7		)	(3.1		)	—		—		1.0		1.1

Gross Amount in Accumulated Other Comprehensive Income	378.3			379.8			51.6		60.5		67.1		82.6
Income Tax Effect	143.1			143.3			5.9		6.3		25.3		30.9

Net Amount in Accumulated Other Comprehensive Income	$	235.2		$	236.5		$	45.7	$	54.2	$	41.8	$	51.7

Components of Company's Net Periodic Benefit Cost



	U.S. PLAN									NON-U.S. PLANS									SUPPLEMENTAL PLAN
($ In Millions)	2015			2014			2013			2015			2014			2013			2015			2014			2013
Service Cost	$	37.8		$	32.7		$	30.3		$	—		$	—		$	—		$	3.6		$	3.1		$	1.6
Interest Cost	44.7			44.4			42.1			5.7			6.9			6.6			5.0			4.8			4.4
Expected Return on Plan Assets	(96.5		)	(97.7		)	(93.3		)	(5.9		)	(7.0		)	(6.2		)	N/A			N/A			N/A
Amortization:
Net Loss (Gain)	29.7			21.5			42.5			1.5			(1.6		)	1.0			7.3			5.8			6.7
Prior Service Cost	(0.4		)	(0.4		)	(0.4		)	—			—			—			0.2			0.5			0.5
Net Periodic Pension Expense (Benefit)	$	15.3		$	0.5		$	21.2		$	1.3		$	(1.7	)	$	1.4		$	16.1		$	14.2		$	13.2
Weighted-Average Assumptions:
Discount Rates	4.25		%	5.00		%	4.25		%	3.20		%	4.31		%	4.42		%	4.25		%	5.00		%	4.25		%
Rate of Increase in Compensation Level	4.25			4.25			4.02			N/A			N/A			N/A			4.25			4.25			4.02
Expected Long-Term Rate of Return on Assets	7.25			7.75			7.75			4.00			4.84			4.76			N/A			N/A			N/A

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



	U.S. PLAN						NON-U.S. PLANS						SUPPLEMENTAL PLAN
(In Millions)	2015			2014			2015			2014			2015			2014
Beginning Balance	$	1,091.5		$	919.7		$	184.6		$	164.7		$	123.0		$	101.5
Service Cost	37.8			32.7			—			—			3.6			3.1
Interest Cost	44.7			44.4			5.7			6.9			5.0			4.8
Actuarial (Gain) Loss	(93.7		)	153.1			(12.0		)	33.2			(8.1		)	23.1
Benefits Paid	(73.8		)	(58.4		)	(9.4		)	(6.6		)	(9.6		)	(9.5		)
Foreign Exchange Rate Changes	—			—			(12.4		)	(13.6		)	—			—

Ending Balance	$	1,006.5		$	1,091.5		$	156.5		$	184.6		$	113.9		$	123.0

Estimated Future Benefit Payments



(In Millions)	U.S. PLAN		NON-U.S. PLANS		SUPPLEMENTAL PLAN
2016	$	68.0	$	2.3	$	9.6
2017	67.8		2.5		12.0
2018	69.2		2.9		11.7
2019	70.8		3.0		13.0
2020	69.1		3.3		11.6
2021-2025	345.6		21.4		55.6

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, 2015 and 2014.

TABLE 95: CHANGE IN LEVEL 3 ASSETS



	PRIVATE EQUITY FUNDS						HEDGE FUNDS
(In Millions)	2015			2014			2015			2014
Fair Value at January 1	$	49.0		$	47.7		$	68.6		$	55.1
Actual Return on Plan Assets	6.6			10.3			(0.2		)	1.8
Realized Gain	—			—			2.6			1.7
Purchases	2.4			3.5			10.0			15.0
Sales	(10.5		)	(12.5		)	(17.6		)	(5.0		)

Fair Value at December 31	$	47.5		$	49.0		$	63.4		$	68.6

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

Other Postretirement Plan

Defined Benefit Plan Disclosure [Line Items]

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 2015 and 2014, and the change in the accumulated postretirement benefit obligation during 2015 and 2014.

TABLE 96: POSTRETIREMENT HEALTH CARE PLAN STATUS



	DECEMBER 31,
(In Millions)	2015		2014
Accumulated Postretirement Benefit Obligation at Measurement Date:
Retirees and Dependents	$	24.9	$	25.0
Actives Eligible for Benefits	7.3		8.4

Net Postretirement Benefit Obligation	$	32.2	$	33.4

Amount Included in Accumulated Other Comprehensive Income



	DECEMBER 31,
(In Millions)	2015			2014
Net Actuarial Gain	$	(2.6	)	$	(2.4	)
Prior Service Cost	—			—

Gross Amount in Accumulated Other Comprehensive Income	(2.6		)	(2.4		)
Income Tax Effect	(1.0		)	(0.9		)

Net Amount in Accumulated Other Comprehensive Income	$	(1.6	)	$	(1.5	)

Components of Company's Net Periodic Benefit Cost



	FOR THE YEAR ENDED DECEMBER 31,
(In Millions)	2015		2014			2013
Service Cost	$	0.1	$	0.1		$	0.1
Interest Cost	1.4		1.5			1.2
Amortization
Net Gain	—		(0.6		)	(1.2		)
Prior Service Benefit	—		—			(3.0		)

Net Periodic Postretirement (Benefit) Expense	$	1.5	$	1.0		$	(2.9	)

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



	FOR THE YEAR ENDED DECEMBER 31,
(In Millions)	2015			2014
Beginning Balance	$	33.4		$	31.2
Service Cost	0.1			0.1
Interest Cost	1.4			1.5
Actuarial Loss	(0.2		)	3.0
Net Claims Paid	(2.5		)	(3.1		)
Medicare Subsidy	—			0.7

Ending Balance	$	32.2		$	33.4

Estimated Future Benefit Payments



(In Millions)	TOTAL POSTRETIREMENT MEDICAL BENEFITS
2016	$	2.8
2017	2.9
2018	3.0
2019	2.9
2020	2.8
2021-2025	11.3