Defined Benefit Plans - Net Periodic Pension and Postretirement Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 250	$ 210		$ 740	$ 680
Interest costs	390	380		1,180	1,210
Expected return on plan assets	(420)	(420)		(1,260)	(1,430)
Amortization of prior service cost	0	0		10	10
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	0	0	$ (2,800)	0	(2,750)
Amortization of net (gain)/loss	230	310		700	1,050
Net periodic benefit cost	450	480		1,370	4,270
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	0	0		0	0
Interest costs	0	10		10	20
Expected return on plan assets	0	0		0	0
Amortization of prior service cost	0	0		0	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	0	0		0	0
Amortization of net (gain)/loss	(10)	(10)		(40)	(30)
Net periodic benefit cost	$ (10)	$ 0		$ (30)	$ (10)