Retirement Plans and Other Post-Retirement Benefits (Tables)

6 Months Ended

Jun. 30, 2018

Compensation And Retirement Disclosure [Abstract]

Schedule of Net Periodic Costs of Pension and Post Retirement Medical Benefit Plans

The following tables provide information with respect to the net periodic costs of our pension and post-retirement medical benefit plans.

	Three months ended June 30
In thousands	2018			2017
Pension Benefits
Service cost	$	2,747		$	2,649
Interest cost		5,626			5,989
Expected return on plan assets		(10,722	)		(10,666	)
Amortization of prior service    cost		781			708
Amortization of unrecognized    loss		3,523			3,311
Total net periodic benefit cost	$	1,955		$	1,991
Other Benefits
Service cost	$	238		$	284
Interest cost		410			513
Amortization of prior    service credit		(46	)		(46	)
Amortization of    actuarial gain		(272	)		(46	)
Total net periodic    benefit cost	$	330		$	705

	Six months ended June 30
In thousands	2018			2017
Pension Benefits
Service cost	$	5,606		$	5,370
Interest cost		11,215			11,896
Expected return on plan assets		(21,561	)		(21,497	)
Amortization of prior service    cost		1,561			1,412
Amortization of unrecognized    loss		6,913			6,133
Total net periodic benefit cost	$	3,734		$	3,314
Other Benefits
Service cost	$	545		$	579
Interest cost		861			998
Amortization of prior    service credit		(91	)		(91	)
Amortization of    actuarial gain		(345	)		(189	)
Total net periodic    benefit cost	$	970		$	1,297