Defined Benefit Plans - Net Periodic Pension and Postretirement Benefit Costs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 170	$ 150	$ 520	$ 450
Interest costs	410	410	1,230	1,210
Expected return on plan assets	(460)	(430)	(1,380)	(1,280)
Amortization of prior service cost	0	0	10	10
Settlement/curtailment (gain)	0	0	0	0
Amortization of net (gain)/loss	320	260	960	790
Net periodic benefit cost	440	390	1,340	1,180
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	20	30	40
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	(70)	0	(200)
Settlement/curtailment (gain)	0	(1,490)	0	(1,490)
Amortization of net (gain)/loss	(20)	(20)	(60)	(60)
Net periodic benefit cost	$ (10)	$ (1,560)	$ (30)	$ (1,710)