Retirement Benefits (Tables)

6 Months Ended

Jun. 30, 2013

Compensation and Retirement Disclosure [Abstract]

Components of Net Periodic Benefit Cost

The components of the net periodic pension benefit costs are as follows:

	Three Months Ended						Six Months Ended
	June 30,			June 30,			June 30,			June 30,
	2013			2012			2013			2012
	(Dollars in thousands)
Service cost	$	3,947		$	3,676		$	8,056		$	7,399
Interest cost	6,624			6,920			13,272			13,829
Expected return on plan assets	(13,156		)	(11,801		)	(26,269		)	(22,314		)
Amortization of prior service cost	421			477			849			953
Amortization of actuarial losses	2,898			3,088			5,885			6,176
Net periodic benefit cost	$	734		$	2,360		$	1,793		$	6,043

The components of the net periodic other postretirement benefits costs are as follows:

	Three Months Ended						Six Months Ended
	June 30,			June 30,			June 30,			June 30,
	2013			2012			2013			2012
	(Dollars in thousands)
Service cost	$	191		$	228		$	392		$	455
Interest cost	443			571			917			1,140
Amortization of prior service credit	(669		)	(654		)	(1,339		)	(1,308		)
Amortization of actuarial losses	49			53			104			142
Net periodic benefit cost	$	14		$	198		$	74		$	429