Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 137	$ 44
Interest cost on projected benefit obligation	1,355	596
Expected return on assets	(1,519)	(955)
Amortization of net loss (gain)	464	139
Net (income) expense	437	(176)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	1	2
Interest cost on projected benefit obligation	97	93
Expected return on assets	0	0
Amortization of net loss (gain)	(19)	(24)
Net (income) expense	$ 79	$ 71