Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Changes in Projected Benefit Obligations

Following is a reconciliation of the changes in plan benefit obligations and fair value of plan assets, and a statement of the funded status (in thousands):



	Pension Benefits						Other Postretirement Benefits
	December 31,						December 31,
	2018			2017			2018			2017
Change in benefit obligation:
Obligation at beginning of period	$	696,796		$	646,032		$	22,921		$	26,217
Service cost	11,776			10,994			398			456
Interest cost	24,420			25,633			578			715
Actuarial loss (gain)	(53,496		)	41,719			(1,903		)	(1,884		)
Settlements	—			—			390			390
Benefits paid	(29,870		)	(27,582		)	(1,773		)	(2,973		)
Benefit Obligation at End of Period	$	649,626		$	696,796		$	20,611		$	22,921
Change in Fair Value of Plan Assets:
Fair value of plan assets at beginning of period	$	586,508		$	524,637		$	20,380		$	18,605
Return on plan assets	(40,528		)	80,253			(866		)	2,690
Employer contributions	9,200			9,200			929			2,058
Benefits paid	(29,870		)	(27,582		)	(1,773		)	(2,973		)
Fair value of plan assets at end of period	$	525,310		$	586,508		$	18,670		$	20,380
Funded Status	$	(124,316	)	$	(110,288	)	$	(1,941	)	$	(2,541	)

Amounts Recognized in the Balance Sheet Consist of:
Noncurrent asset	2,672			2,535			4,565			5,061
Total Assets	2,672			2,535			4,565			5,061
Current liability	—			—			(2,271		)	(3,353		)
Noncurrent liability	(126,988		)	(112,823		)	(4,235		)	(4,249		)
Total Liabilities	(126,988		)	(112,823		)	(6,506		)	(7,602		)
Net amount recognized	$	(124,316	)	$	(110,288	)	$	(1,941	)	$	(2,541	)

Amounts Recognized in Regulatory Assets Consist of:
Prior service (cost) credit	—			(4		)	7,922			9,955
Net actuarial loss	(116,425		)	(105,545		)	(1,910		)	(1,735		)
Amounts recognized in AOCL consist of:
Prior service cost	—			—			(548		)	(698		)
Net actuarial gain	—			—			1,260			1,079
Total	$	(116,425	)	$	(105,549	)	$	6,724		$	8,601

Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets

The total projected benefit obligation and fair value of plan assets for the pension plans with accumulated benefit obligations in excess of plan assets were as follows (in millions):



	NorthWestern Energy Pension Plan
	December 31,
	2018		2017
Projected benefit obligation	$	592.5	$	634.4
Accumulated benefit obligation	592.5		634.4
Fair value of plan assets	466.7		522.7

____________________

As of December 31, 2018, the fair value of the NorthWestern Corporation pension plan assets exceed the total projected and accumulated benefit obligation and are therefore excluded from this table.

Schedule of Defined Benefit Plans Disclosures

The components of the net costs (credits) for our pension and other postretirement plans are as follows (in thousands):



	Pension Benefits									Other Postretirement Benefits
	December 31,									December 31,
	2018			2017			2016			2018			2017			2016
Components of Net Periodic Benefit Cost
Service cost	$	11,776		$	10,994		$	11,759		$	398		$	456		$	492
Interest cost	24,420			25,633			26,210			578			715			795
Expected return on plan assets	(28,207		)	(23,964		)	(28,248		)	(954		)	(846		)	(1,042		)
Amortization of prior service cost (credit)	4			4			246			(1,882		)	(1,882		)	(1,882		)
Recognized actuarial loss	4,360			7,837			9,888			(79		)	318			315
Settlement loss recognized	—			—			—			390			390			390
Net Periodic Benefit Cost (Credit)	$	12,353		$	20,504		$	19,855		$	(1,549	)	$	(849	)	$	(932	)

Schedule of Assumptions Used

The weighted-average assumptions used in calculating the preceding information are as follows:



	Pension Benefits						Other Postretirement Benefits
	December 31,						December 31,
	2018		2017		2016		2018		2017		2016
Discount rate	4.15-4.20	%	3.50-3.60	%	3.95-4.10	%	3.90-3.95	%	3.20-3.30	%	3.40-3.55	%
Expected rate of return on assets	4.47-4.97		4.70		5.80		4.82		4.70		5.80
Long-term rate of increase in compensation levels (nonunion)	2.84		2.89		3.28		2.84		2.89		3.28
Long-term rate of increase in compensation levels (union)	2.03		2.03		3.20		2.03		2.03		3.20
Interest crediting rate	4.00-6.00		4.00-6.00		4.20-6.00		N/A		N/A		N/A

Schedule of Pension And Postretirement Benefits Investment Strategy

Based on this, the target asset allocation established, within an allowable range of plus or minus 5%, is as follows:



	NorthWestern Energy Pension				NorthWestern Corporation Pension				NorthWestern Energy Health and Welfare
	December 31,				December 31,				December 31,
	2018		2017		2018		2017		2018		2017
Domestic debt securities	55.0	%	55.0	%	75.0	%	70.0	%	40.0	%	40.0	%
International debt securities	4.0		4.0		2.5		2.5		—		—
Domestic equity securities	16.5		16.5		9.0		11.0		50.0		50.0
International equity securities	24.5		24.5		13.5		16.5		10.0		10.0

Schedule of Allocation of Plan Assets

The actual allocation by plan is as follows:



	NorthWestern Energy Pension				NorthWestern Corporation Pension				NorthWestern Energy Health and Welfare
	December 31,				December 31,				December 31,
	2018		2017		2018		2017		2018		2017
Cash and cash equivalents	0.1	%	0.1	%	—	%	—	%	1.0	%	1.5	%
Domestic debt securities	57.5		54.5		81.3		70.0		40.8		35.2
International debt securities	4.4		4.0		2.6		2.5		—		—
Domestic equity securities	15.0		16.7		6.3		11.1		49.1		53.4
International equity securities	23.0		24.7		9.8		16.4		9.1		9.9
	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%

Schedule of Pension Contributions

Annual contributions to each of the pension plans are as follows (in thousands):



	2018		2017		2016
NorthWestern Energy Pension Plan (MT)	$	8,000	$	8,000	$	11,500
NorthWestern Corporation Pension Plan (SD and NE)	1,200		1,200		1,200
	$	9,200	$	9,200	$	12,700

Schedule of Expected Benefit Payments

We estimate the plans will make future benefit payments to participants as follows (in thousands):



	Pension Benefits		Other Postretirement Benefits
2019	$	32,618	$	3,208
2020	33,880		2,785
2021	35,391		2,731
2022	36,726		2,432
2023	38,124		2,186
2024-2028	206,071		6,606