Equity Method Investments - Operating Results (Details) - ICP [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of Equity Method Investments [Line Items]
Net sales	$ 40,576	$ 48,371	$ 90,185	$ 87,969
Cost of sales and expenses	36,980	37,609	84,866	72,779
Net income	$ 3,596	$ 10,762	$ 5,319	$ 15,190