Defined Benefit Plans - Net Periodic Pension and Postretirement Benefit Costs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 190	$ 170	$ 380	$ 350
Interest costs	440	410	880	820
Expected return on plan assets	(520)	(460)	(1,040)	(920)
Amortization of prior service cost	10	10	10	10
Amortization of net (gain)/loss	280	320	560	640
Net periodic benefit cost	400	450	790	900
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	10	10	20	20
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of net (gain)/loss	(30)	(20)	(50)	(40)
Net periodic benefit cost	$ (20)	$ (10)	$ (30)	$ (20)