Employee Benefit Plans - Net Periodic Pension and Postretirement Benefit Costs (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 950	$ 890	$ 760
Interest costs	1,510	1,580	1,760
Expected return on plan assets	(1,610)	(1,840)	(2,070)
Settlements and curtailments loss	1,330	2,750	0
Amortization of net (gain)/loss	930	1,340	1,120
Net periodic benefit cost (income)	$ 3,110	$ 4,720	$ 1,570