Employee Benefit Plans (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Components of net periodic benefit cost
Service cost	$ 227	$ 198	$ 191
Interest cost	970	882	934
Expected return on plan assets	(1,251)	(1,114)	(1,010)
Recognized actuarial loss (gain)	269	767	705
Amortization of prior service cost (gain)	8	8	8
Curtailment gain recognized	0	0	0
Total net periodic benefit cost	223	741	828
Postretirement Benefits [Member]
Components of net periodic benefit cost
Service cost	0	1	1
Interest cost	3	4	4
Expected return on plan assets	0	0	0
Recognized actuarial loss (gain)	(55)	(76)	(80)
Amortization of prior service cost (gain)	(3)	(391)	(391)
Curtailment gain recognized	0	(1,698)	0
Total net periodic benefit cost	$ (55)	$ (2,160)	$ (466)