Pension and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2018

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]

Schedule of Net Benefit Costs

The net periodic benefit cost for the three months ended March 31, 2018 and 2017 includes the following components: 

	Pension Benefits						Postretirement Benefits
	Three Months Ended   March 31,						Three Months Ended   March 31,
Components of Net Periodic Benefit Cost	2018			2017			2018			2017
Selling, general, and administrative expenses:
Service cost	$	7,100		$	6,700		$	575		$	575
Non-operating expenses:
Interest cost	6,975			7,000			650			700
Expected return on plan assets	(8,075		)	(7,725		)	—			—
Amortization of:
Net actuarial loss	6,725			5,300			225			225
Prior service cost (gain)	75			100			(500		)	(550		)
Net periodic benefit cost	$	12,800		$	11,375		$	950		$	950