Pension and Postretirement Benefits

3 Months Ended

Mar. 31, 2016

Compensation And Retirement Disclosure [Abstract]

Pension and Postretirement Benefits

6. Pension and Postretirement Benefits

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Three Months Ended March 31,
	Pension						Postretirement Benefits
	2016			2015			2016			2015
	(Dollars in Thousands)
Service cost	$	5,507		$	6,290		$	34		$	39
Interest cost		8,871			8,112			238			230
Expected return on assets		(9,434	)		(9,104	)		—			—
Amortization of:
Prior service cost (credit)		88			105			(462	)		(576	)
Actuarial loss (gain)		2,831			3,108			(99	)		(82	)
Settlement charge		59			—			—			—
Special termination benefit		126			256			—			—
Net periodic benefit cost (credit)	$	8,048		$	8,767		$	(289	)	$	(389	)