Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 133	$ 131	$ 398	$ 392
Interest cost on projected benefit obligation	1,205	1,549	3,803	4,647
Expected return on assets	(1,814)	(2,130)	(5,627)	(6,389)
Settlement loss	0	0	1,607	0
Amortization of net loss (gain)	254	269	823	806
Net (income) expense	(222)	(181)	1,004	(544)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	2	2	6	7
Interest cost on projected benefit obligation	93	108	278	323
Expected return on assets	0	0	0	0
Settlement loss	0	0	0	0
Amortization of net loss (gain)	(24)	(15)	(73)	(45)
Net (income) expense	$ 71	$ 95	$ 211	$ 285