Retirement Plans - Components of Net Periodic Pension (Credit) Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Retirement Benefits [Abstract]
Interest cost	$ 600	$ 500
Expected return on plan assets	(700)	(800)
Amortization of net actuarial loss	100	100
Net periodic pension credit		(200)
Settlement loss		(100)
Total pension (credit) cost		$ (200)