Organization and Significant Accounting Policies, Inventory Valuation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Inventory Valuation [Abstract]
Inventory write-off	$ 0	$ 0	$ 0
Inventories	$ 9,982	$ 7,489