Components of Net Periodic Benefit Cost (Tables)

6 Months Ended

Jun. 30, 2017

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

	Three Months Ended June 30,										Six Months Ended June 30,
	(000's)										(000's)
	Pension Benefits						Post-Retirement Health Benefits				Pension Benefits						Post-Retirement Health Benefits
	2017			2016			2017		2016		2017			2016			2017		2016
Service cost	$	358		$	470		$	13	$	14	$	716		$	941		$	26	$	27
Interest cost	905			932			43		46		1,810			1,865			86		93
Expected return on plan assets	(985		)	(857		)	—		—		(1,970		)	(1,715		)	—		—
Net amortization of net (gain) loss	301			484			—		—		602			967			—		—
Net Periodic Benefit Cost	$	579		$	1,029		$	56	$	60	$	1,158		$	2,058		$	112	$	120