Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 2,258	$ 2,271
Expected return on plan assets	(2,723)	(3,081)
Net benefit credit	(465)	(810)
Other postretirement benefits plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	120	140
Interest cost	876	918
Net benefit credit	$ 996	$ 1,058