Benefit Plans (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
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	17	11	51	35
Interest cost	318	364	955	1,094
Expected return on plan assets	(547)	(473)	(1,642)	(1,421)
Amortization of net loss (gain)	129	103	387	307
Amortization of prior service credit	0	0	0	0
Net periodic expense (benefit)	(83)	5	(249)	15
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	12	7	38	23
Interest cost	25	26	76	77
Expected return on plan assets	(122)	(113)	(371)	(338)
Amortization of net loss (gain)	(12)	(4)	(37)	(14)
Amortization of prior service credit	(66)	(66)	(197)	(197)
Net periodic expense (benefit)	$ (163)	$ (150)	$ (491)	$ (449)