Employee Benefit Plans

9 Months Ended

Sep. 30, 2015

Compensation and Retirement Disclosure [Abstract]

Employee Benefit Plans

Employee Benefit Plans

We sponsor two pension plans for certain union employees and a pension plan primarily for non-union 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, 2014 and 2015 (in thousands):

	Three Months Ended						Three Months Ended
	September 30, 2014						September 30, 2015
	Pension Benefits			Other  Postretirement Benefits			Pension Benefits			Other  Postretirement Benefits
Components of net periodic benefit costs:
Service cost	$	3,348		$	57		$	4,723		$	61
Interest cost	1,332			126			1,938			109
Expected return on plan assets	(1,588		)	—			(2,009		)	—
Amortization of prior service credit	—			(928		)	—			(928		)
Amortization of actuarial loss	756			229			1,577			221
Settlement cost	30			—			—			—
Net periodic benefit cost (credit)	$	3,878		$	(516	)	$	6,229		$	(537	)

	Nine Months Ended						Nine Months Ended
	September 30, 2014						September 30, 2015
	Pension Benefits			Other  Postretirement Benefits			Pension Benefits			Other  Postretirement Benefits
Components of net periodic benefit costs:
Service cost	$	10,052		$	171		$	14,168		$	183
Interest cost	5,021			379			5,815			328
Expected return on plan assets	(4,775		)	—			(6,028		)	—
Amortization of prior service cost (credit)	33			(2,784		)	—			(2,784		)
Amortization of actuarial loss	2,315			686			4,730			663
Settlement cost	1,599			—			—			—
Net periodic benefit cost (credit)	$	14,245		$	(1,548	)	$	18,685		$	(1,610	)

Contributions estimated to be paid into the plans in 2015 are $21.1 million and $1.2 million for the pension and other postretirement benefit plans, respectively.

We match our employees' qualifying contributions to our defined contribution plan, resulting in expense to us. Expenses related to the defined contribution plan were $1.7 million and $1.8 million, respectively, for the three months ended September 30, 2014 and 2015, and $6.3 million and $6.8 million, respectively, for the nine months ended September 30, 2014 and 2015.

Amounts Included in AOCL

The changes in AOCL related to employee benefit plan assets and benefit obligations for the three and nine months ended September 30, 2014 and 2015 were as follows (in thousands):

	Three Months Ended						Three Months Ended
	September 30, 2014						September 30, 2015
Gains (Losses) Included in AOCL	Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits
Beginning balance	$	(33,023	)	$	1,654		$	(60,104	)	$	(3,110	)
Amortization of prior service credit	—			(928		)	—			(928		)
Amortization of actuarial loss	756			229			1,577			221
Settlement cost	30			—			—			—
Ending balance	$	(32,237	)	$	955		$	(58,527	)	$	(3,817	)

	Nine Months Ended						Nine Months Ended
	September 30, 2014						September 30, 2015
Gains (Losses) Included in AOCL	Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits
Beginning balance	$	(36,184	)	$	3,053		$	(63,257	)	$	(1,696	)
Amortization of prior service cost (credit)	33			(2,784		)	—			(2,784		)
Amortization of actuarial loss	2,315			686			4,730			663
Settlement cost	1,599			—			—			—
Ending balance	$	(32,237	)	$	955		$	(58,527	)	$	(3,817	)