Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Schedule of Consolidated Net Periodic Benefit Costs

Net periodic benefit expense for the three months ended March 31, 2017 and 2018 was as follows (in thousands):

	Three Months Ended					Three Months Ended
	March 31, 2017					March 31, 2018
	Pension Benefits			Other  Postretirement Benefits		Pension Benefits			Other  Postretirement Benefits
Components of net periodic benefit costs:
Service cost	$	5,018		$	65	$	15,700		$	65
Interest cost	2,350			122		6,443			106
Expected return on plan assets	(2,487		)	—		(2,978		)	—
Amortization of prior service credit	(45		)	—		(45		)	—
Amortization of actuarial loss	1,028			200		4,954			160
Settlement cost	1,365			—		—			—
Net periodic benefit cost	$	7,229		$	387	$	24,074		$	331

The service component of our net periodic benefit costs is presented in operating expense and G&A expense, and the non-service components are presented in other expense in our consolidated statements of income.

Schedule of Amounts Recognized in Other Comprehensive Loss

The changes in AOCL related to employee benefit plan assets and benefit obligations for the three months ended March 31, 2017 and 2018 were as follows (in thousands):

	Three Months Ended						Three Months Ended
	March 31, 2017						March 31, 2018
Gains (Losses) Included in AOCL	Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits
Beginning balance	$	(58,584	)	$	(7,881	)	$	(97,226	)	$	(6,597	)
Net actuarial loss	—			—			(5,944		)	—
Amortization of prior service credit	(45		)	—			(45		)	—
Amortization of actuarial loss	1,028			200			4,954			160
Settlement cost	1,365			—			—			—
Ending balance	$	(56,236	)	$	(7,681	)	$	(98,261	)	$	(6,437	)