Defined Benefit Plans - Net Periodic Pension and Postretirement Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 250	$ 240
Interest costs	400	420
Expected return on plan assets	(420)	(520)
Amortization of net (gain)/loss	230	380
Net periodic benefit cost	460	520
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	0	0
Interest costs	0	10
Expected return on plan assets	0	0
Amortization of net (gain)/loss	(10)	(10)
Net periodic benefit cost	$ (10)	$ 0