Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 133	$ 147
Interest cost on projected benefit obligation	1,215	1,122
Expected return on assets	(1,219)	(1,393)
Amortization of prior service cost	0	0
Amortization of net loss (gain)	501	452
Net expense	630	328
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	0	1
Interest cost on projected benefit obligation	87	82
Expected return on assets	0	0
Amortization of prior service cost	(1)	0
Amortization of net loss (gain)	(44)	(10)
Net expense	$ 44	$ 73