Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Components of net periodic benefit cost [Abstract]
Contribution made to pension and postretirement plans	$ 0
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	18	14
Interest cost	336	315
Expected return on plan assets	(609)	(498)
Amortization of net loss (gain)	0	147
Amortization of prior service credit	0	0
Net periodic benefit	(255)	(22)
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	14	12
Interest cost	32	24
Expected return on plan assets	(169)	(123)
Amortization of net loss (gain)	(72)	(15)
Amortization of prior service credit	(45)	(66)
Net periodic benefit	$ (240)	$ (168)