Defined Benefit Pension Plans Components of Pension Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs--increase in benefit obligation earned	$ 400	$ 530	$ 370
Interest cost on projected benefit obligation	718	1,002	1,243
Expected return on plan assets	(231)	(638)	(1,044)
Curtailment loss	0	0	0
Settlement loss	5,499	3,849	2,346
Amortization of net actuarial loss	728	909	951
Amortization of prior service cost	64	64	0
Net pension expense of defined benefit pension plans	$ 7,178	$ 5,716	$ 3,866