Inventories (Summary of Activity within the Reserve for Excess, Obsolete, and Slow Moving Inventory) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory [Roll Forward]
Beginning balance	$ 3,695	$ 3,801	$ 7,428
Excess, obsolete and slow moving inventory expense	729	1,276	(239)
Scrapped inventory and other adjustments	(252)	(1,382)	(3,388)
Ending balance	$ 4,172	$ 3,695	$ 3,801