Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
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	$ 15	$ 8	45	$ 44
Interest cost	337	359	997	1,031
Expected return on plan assets	(684)	(660)	(2,052)	(1,878)
Amortization of net loss (gain)	77	0	158	0
Amortization of prior service cost	0	0	0	0
Net periodic benefit	(255)	(293)	(852)	(803)
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	47	46	125	75
Interest cost	72	99	201	163
Expected return on plan assets	(182)	(166)	(543)	(504)
Amortization of net loss (gain)	(34)	(77)	(105)	(223)
Amortization of prior service cost	23	239	68	149
Net periodic benefit	$ (74)	$ 141	$ (254)	$ (340)