Long-term Debt and Line of Credit Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Aug. 05, 2015
Debt Instrument [Line Items]
Principal current			$ 23,500,000	$ 19,813,000
Principal			88,750,000	104,563,000
Deferred Finance Costs, current			(744,000)	(625,000)
Deferred Issuance Costs			(2,809,000)	(3,298,000)
Net Value, current			22,756,000	19,188,000
Long-term Debt, Excluding Current Maturities			63,185,000	82,077,000
Total debt			85,941,000	101,265,000
Hedging Liabilities, Noncurrent			26,000	382,000
Debt issuance cost			4,500,000
Debt issuance expense	$ 600,000	$ 200,000	$ 500,000
Line of Credit
Debt Instrument [Line Items]
Stated interest rate					4.75%
Debt, weighted average interest rate			3.80%
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Principal current			$ 10,000,000	8,000,000
Deferred Finance Costs, current			(317,000)	(252,000)
Net Value, current			$ 9,683,000	7,748,000
Line of credit facility, maximum borrowing capacity					$ 50,000,000
Stated interest rate			5.00%
Term Loan | Line of Credit
Debt Instrument [Line Items]
Total debt			$ 78,750,000
Line of credit facility, maximum borrowing capacity			135,000,000		$ 135,000,000
Term loan-current | Loans Payable
Debt Instrument [Line Items]
Principal current			13,500,000	11,813,000
Deferred Finance Costs, current			(427,000)	(373,000)
Net Value, current			13,073,000	11,440,000
Term loan-long-term | Loans Payable
Debt Instrument [Line Items]
Principal, long-term			65,250,000	84,750,000
Deferred Issuance Costs, long-term			(2,065,000)	(2,673,000)
Long-term Debt, Excluding Current Maturities			63,185,000	82,077,000
Long-term Debt | Accounting Standards Update 2015-03
Debt Instrument [Line Items]
Deferred Issuance Costs			(2,100,000)	(2,700,000)
Short-term Debt | Accounting Standards Update 2015-03
Debt Instrument [Line Items]
Deferred Issuance Costs			$ (700,000)	$ (600,000)