Employee Benefit Plans:

3 Months Ended

Mar. 31, 2019

Defined Benefit Plan [Abstract]

Employee Benefit Plans

EMPLOYEE BENEFIT PLANS

Defined Benefit Pension Plan

The components of net periodic benefit cost for the Defined Benefit Pension Plan were as follows (in thousands):

	Three Months Ended March 31,
	2019			2018
Service cost	$	1,346		$	1,708
Interest cost	4,343			3,867
Expected return on plan assets	(6,100		)	(6,185		)
Prior service cost	6			15
Net loss (gain)	941			2,158
Net periodic benefit cost	$	536		$	1,563

Defined Benefit Postretirement Healthcare Plans

The components of net periodic benefit cost for the Defined Benefit Postretirement Healthcare Plans were as follows (in thousands):

	Three Months Ended March 31,
	2019			2018
Service cost	$	454		$	573
Interest cost	560			521
Expected return on plan assets	(57		)	(57		)
Prior service cost (benefit)	(99		)	(99		)
Net loss (gain)	—			54
Net periodic benefit cost	$	858		$	992

Supplemental Non-qualified Defined Benefit and Defined Contribution Plans

The components of net periodic benefit cost for the Supplemental Non-qualified Defined Benefit and Defined Contribution Plans were as follows (in thousands):

	Three Months Ended March 31,
	2019		2018
Service cost (a)	$	1,285	$	280
Interest cost	324		293
Net loss (gain)	134		250
Net periodic benefit cost	$	1,743	$	823

__________

(a) The increase in service cost for the three months ended March 31, 2019 compared to the same period in 2018 is primarily driven by market returns.

Contributions

Contributions to the Defined Benefit Pension Plan are cash contributions made directly to the Pension Plan Trust account. Contributions to the Postretirement Healthcare and Supplemental Plans are made in the form of benefit payments. Contributions made in 2019 and anticipated contributions for 2019 and 2020 are as follows (in thousands):

	Contributions Made		Additional Contributions		Contributions
	Three Months Ended March 31, 2019		Anticipated for 2019		Anticipated for 2020
Defined Benefit Pension Plan	$	—	$	12,700	$	12,700
Non-pension Defined Benefit Postretirement Healthcare Plans	$	1,109	$	3,326	$	4,271
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	366	$	1,097	$	1,562