Debt - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Line of Credit Facility, Initiation Date		Oct. 30, 2015
Long-term debt	$ 3,640,000	$ 4,435,000
Maximum amount outstanding	12,800,000	6,000,000
Average amount outstanding	$ 4,100,000	$ 2,200,000
Weighted-average interest rate	3.40%	3.00%
Commitment fees	$ 300,000	$ 100,000
Interest expense	$ 200,000	$ 100,000
Debt covenants, Maximum leverage ratio	1.10%
Debt covenants, Minimum tangible net worth	$ 5,000,000
Debt covenants, Maximum capital expenditures	5,000,000
Debt covenants threshold limit to test fixed charge coverage ratio	5,625,000
Total available borrowings	30,600,000
Debt covenants, EBITDA	8,000,000
Capital expenditures	$ 2,200,000
Federal Funds Effective Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
Minimum [Member] | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.50%
Minimum [Member] | Adjusted London Interbank Offered Rate L I B O R
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
Maximum [Member] | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate		2.00%
Maximum [Member] | Adjusted London Interbank Offered Rate L I B O R
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
Credit and Security Agreement [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, term		3 years
Line of Credit Facility, Maximum Borrowing Capacity		$ 45,000,000
Line of credit facility, expiration date		2020-12
Swing Line Loans [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 10,000,000
Letters of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 10,000,000