Valuation Allowances and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Allowance for Doubtful Accounts Receivable, beginning of period	$ 870	$ 969	$ 1,656
Valuation Allowances and Reserves, Charged to Cost and Expense	1,246	760	599
Valuation Allowances and Reserves, Charged to Other Accounts	0	0	0
Valuation Allowances and Reserves, Deductions	826	859	1,286
Allowance for Doubtful Accounts Receivable, end of period	$ 1,290	$ 870	$ 969