Investments (Summarized Financial Information of Unconsolidated Entities) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Investments
Sales	$ 15,222
Total expenses	10,960
Net income	4,262
Current assets	21,780	$ 27,779
Noncurrent assets	183,371	152,112
Current liabilities	$ 12,078	$ 16,577