Accounts Receivable (Allowance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts:
Balance, beginning of period	$ 115	$ 171	$ 193
Provisions for losses on accounts receivables, net of adjustments	(25)	(48)	0
Accounts receivable written off, net of recoveries	0	(8)	(22)
Balance, end of period	$ 90	$ 115	$ 171