Employee Benefits - Components of Net Periodic Pension Cost and Other Changes in Plan Assets and Benefit (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of Net Periodic Pension Cost
Interest cost on projected benefit obligation	$ 989	$ 978	$ 2,967	$ 2,912
Expected return on plan assets	(1,181)	(1,566)	(3,541)	(4,700)
Net amortization	395	512	1,184	1,601
Net Periodic Pension Expense	$ 203	$ (76)	$ 610	$ (187)