Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The following table summarizes key information related to the Company's pension plans and other postretirement benefits:

	Pension Benefits						Pension Benefits						Other Postretirement Benefits						Other Postretirement Benefits
	Three Months Ended						Six Months Ended						Three Months Ended						Six Months Ended
	June 30,						June 30,						June 30,						June 30,
	2017			2016			2017			2016			2017			2016			2017			2016
Service cost — benefits earned during the period	$	141		$	137		$	282		$	274		$	1		$	1		$	3		$	2
Interest cost on projected benefit obligation	1,266			1,355			2,530			2,710			92			97			184			194
Expected return on assets	(1,356		)	(1,519		)	(2,712		)	(3,038		)	—			—			—			—
Amortization of net loss (gain)	502			464			1,004			928			(13		)	(19		)	(27		)	(38		)
Net expense	$	553		$	437		$	1,104		$	874		$	80		$	79		$	160		$	158