Equity Method Investments - Operating Results (Details) - ICP [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Equity Method Investments [Line Items]
Net sales	$ 38,385	$ 49,609
Cost of sales and expenses	36,814	47,886
Net income	$ 1,571	$ 1,723