EMPLOYEE BENEFIT PLANS (Notes)

3 Months Ended

Mar. 31, 2020

Employee Benefit Plans [Line Items]

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS

The following tables set forth the components of net periodic benefit cost for our pension and other postemployment benefit plans for the periods indicated:

	Pension Benefits
	Three Months Ended
	March 31,
	2020			2019
	(Thousands of dollars)
Components of net periodic benefit cost
Service cost	$	3,217		$	3,008
Interest cost	8,545			10,168
Expected return on assets	(15,280		)	(15,485		)
Amortization of net loss	10,580			8,260
Net periodic benefit cost	$	7,062		$	5,951

	Other Postemployment Benefits
	Three Months Ended
	March 31,
	2020			2019
	(Thousands of dollars)
Components of net periodic benefit cost (credit)
Service cost	$	423		$	434
Interest cost	1,889			2,329
Expected return on assets	(3,867		)	(3,147		)
Amortization of unrecognized prior service credit	(29		)	(168		)
Amortization of net loss	43			561
Net periodic benefit cost (credit)	$	(1,541	)	$	9

We recover qualified pension benefit plan and other postemployment benefit plan costs through rates charged to our customers. Certain regulatory authorities require that the recovery of these costs be based on specific guidelines. The difference between these regulatory-based amounts and the periodic benefit cost calculated pursuant to GAAP is deferred as a regulatory asset or liability and amortized to expense over periods in which this difference will be recovered in rates, as authorized by the applicable regulatory authorities. Regulatory deferrals related to net periodic benefit cost were not material for the three months ended March 31, 2020 and 2019.

We continue to capitalize all eligible service cost and non-service cost components under the accounting requirements of ASC Topic 980 (Regulated Operations) for rate-regulated entities. Our consolidated balance sheets reflect the capitalized non-service cost components as a regulatory asset. We have recognized a regulatory asset of $5.4 million and $4.7 million as of March 31, 2020 and December 31, 2019, respectively. See Note 3 of the Notes to Consolidated Financial Statements in this Quarterly Report for additional information.