Pension Benefits and Other Postretirement Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2015

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Components of net periodic benefit cost

The components of net periodic benefit cost (income) for the periods indicated were:

(Dollars in thousands)	Pension Benefits												Retirement Health and Life Insurance Benefits
	Three Months Ended						Six Months Ended						Three Months Ended				Six Months Ended
Change in benefit obligation:	June 30, 2015			June 30, 2014			June 30, 2015			June 30, 2014			June 30, 2015		June 30, 2014		June 30, 2015		June 30, 2014
Service cost	$	—		$	—		$	—		$	—		$	150	$	159	$	300	$	319
Interest cost	1,838			1,990			3,677			4,008			75		84		150		167
Expected return on plan assets	(2,771		)	(3,228		)	(5,542		)	(6,455		)	—		—		—		—
Amortization of net loss	413			160			826			343			—		30		—		61
Settlement charge	—			(33		)	—			77			—		—		—		—
Net periodic benefit cost (income)	$	(520	)	$	(1,111	)	$	(1,039	)	$	(2,027	)	$	225	$	273	$	450	$	547