Employee Benefit Plans

We sponsor two union pension plans for certain union employees and a pension plan primarily for salaried employees, a postretirement benefit plan for selected employees and a defined contribution plan. The following tables present our consolidated net periodic benefit costs related to the pension and postretirement benefit plans for the three and six months ended June 30, 2013 and 2014 (in thousands):



	Three Months Ended						Three Months Ended
	June 30, 2013						June 30, 2014
	Pension Benefits			Other Post- Retirement Benefits			Pension Benefits			Other Post- Retirement Benefits
Components of net periodic benefit costs:
Service cost	$	3,374		$	67		$	3,352		$	47
Interest cost	1,334			91			2,030			139
Expected return on plan assets	(1,645		)	—			(1,490		)	—
Amortization of prior service cost (credit)⁽¹⁾	77			(928		)	—			(928		)
Amortization of actuarial loss⁽¹⁾	1,145			209			930			262
Settlement cost⁽¹⁾	—			—			1,569			—
Net periodic benefit cost (credit)	$	4,285		$	(561	)	$	6,391		$	(480	)



	Six Months Ended						Six Months Ended
	June 30, 2013						June 30, 2014
	Pension Benefits			Other Post- Retirement Benefits			Pension Benefits			Other Post- Retirement Benefits
Components of net periodic benefit costs:
Service cost	$	6,950		$	144		$	6,704		$	114
Interest cost	2,684			206			3,689			253
Expected return on plan assets	(3,115		)	—			(3,187		)	—
Amortization of prior service cost (credit)⁽¹⁾	154			(1,856		)	33			(1,856		)
Amortization of actuarial loss⁽¹⁾	2,167			517			1,559			457
Settlement cost⁽¹⁾	—			—			1,569			—
Net periodic benefit cost (credit)	$	8,840		$	(989	)	$	10,367		$	(1,032	)

(1) These amounts are included in our Consolidated Statements of Comprehensive Income and Consolidated Statements of Cash Flows as changes in employee benefit plan assets and benefit obligations.

Contributions estimated to be paid into the plans in 2014 are $21.1 million and $0.7 million for the pension and postretirement benefit plans, respectively.