Employee Benefit Plans (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Amounts recognized in the consolidated balance sheets
Employee benefit plan assets	$ 0	$ 14,328
Employee benefit plan obligations	(59,308)	(39,477)
Pension Benefits
Amounts recognized in the consolidated balance sheets
Accrued expenses	(165)	(254)
Employee benefit plan assets	0	14,328
Employee benefit plan obligations	(17,778)	(6,824)
Net amount recognized	(17,943)	7,250
Postretirement Benefits
Amounts recognized in the consolidated balance sheets
Accrued expenses	(1,274)	(1,244)
Employee benefit plan assets	0	0
Employee benefit plan obligations	(41,012)	(32,139)
Net amount recognized	$ (42,286)	$ (33,383)