Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 133	$ 147	$ 400	$ 441
Interest cost on projected benefit obligation	1,215	1,124	3,645	3,370
Expected return on assets	(1,218)	(1,393)	(3,655)	(4,179)
Amortization of prior service cost	0	0	0	0
Amortization of net loss (gain)	500	451	1,502	1,354
Net expense	630	329	1,892	986
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	0	2	1	3
Interest cost on projected benefit obligation	87	82	260	246
Expected return on assets	0	0	0	0
Amortization of prior service cost	1	0	3	0
Amortization of net loss (gain)	(9)	(10)	(63)	(30)
Net expense	$ 79	$ 74	$ 201	$ 219