Employee Benefits Plans (Details 13) - Other Postretirement Benefits - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Amounts recognized in the Consolidated Balance Sheets
Current liability	$ 1,624	$ 2,112
Noncurrent liability	20,002	26,889
Net amount recognized	21,626	29,001
Amounts recognized in accumulated other comprehensive loss (pre-tax)
Prior service credit	(616)	(2,527)
Net actuarial gain	(11,825)	(5,933)
Net amount recognized	$ (12,441)	$ (8,460)