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 nine months ended September 30, 2013 and 2014 (in thousands):



	Three Months Ended						Three Months Ended
	September 30, 2013						September 30, 2014
	Pension Benefits			Other Post- Retirement Benefits			Pension Benefits			Other Post- Retirement Benefits
Components of net periodic benefit costs:
Service cost	$	3,476		$	72		$	3,348		$	57
Interest cost	1,342			103			1,332			126
Expected return on plan assets	(1,556		)	—			(1,588		)	—
Amortization of prior service cost (credit)⁽¹⁾	76			(928		)	—			(928		)
Amortization of actuarial loss⁽¹⁾	1,084			259			756			229
Settlement cost⁽¹⁾	—			—			30			—
Net periodic benefit cost (credit)	$	4,422		$	(494	)	$	3,878		$	(516	)



	Nine Months Ended						Nine Months Ended
	September 30, 2013						September 30, 2014
	Pension Benefits			Other Post- Retirement Benefits			Pension Benefits			Other Post- Retirement Benefits
Components of net periodic benefit costs:
Service cost	$	10,426		$	216		$	10,052		$	171
Interest cost	4,026			309			5,021			379
Expected return on plan assets	(4,671		)	—			(4,775		)	—
Amortization of prior service cost (credit)⁽¹⁾	230			(2,784		)	33			(2,784		)
Amortization of actuarial loss⁽¹⁾	3,251			776			2,315			686
Settlement cost⁽¹⁾	—			—			1,599			—
Net periodic benefit cost (credit)	$	13,262		$	(1,483	)	$	14,245		$	(1,548	)

(1) These amounts are included in our Consolidated Statements of Comprehensive Income and cumulatively in our 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.