Pension and Postretirement Benefits

9 Months Ended

Sep. 30, 2015

Compensation And Retirement Disclosure [Abstract]

Pension and Postretirement Benefits

8. 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 September 30,
	Pension						Postretirement Benefits
	2015			2014			2015			2014
	(Dollars in Thousands)
Service cost	$	5,752		$	4,996		$	34		$	57
Interest cost		8,287			7,979			232			302
Expected return on assets		(9,095	)		(8,627	)		—			—
Amortization of:
Prior service cost (credit)		106			111			(574	)		(814	)
Actuarial loss (gain)		3,223			1,011			(77	)		(66	)
Special termination benefit		382			13,680			—			—
Net periodic benefit cost (credit)	$	8,655		$	19,150		$	(385	)	$	(521	)

	Nine Months Ended September 30,
	Pension						Postretirement Benefits
	2015			2014			2015			2014
	(Dollars in Thousands)
Service cost	$	17,257		$	12,129		$	103		$	150
Interest cost		24,863			20,952			696			861
Expected return on assets		(27,285	)		(24,030	)		—			—
Amortization of:
Prior service cost (credit)		317			334			(1,724	)		(2,441	)
Actuarial loss (gain)		13,923			3,034			(232	)		(199	)
Special termination benefit		1,844			13,680			—			—
Net periodic benefit cost (credit)	$	30,919		$	26,099		$	(1,157	)	$	(1,629	)