Line of Credit and Long-Term Debt - Additional Information (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) covenant	Sep. 30, 2013 USD ($)	Dec. 31, 2017 USD ($)
Promissory note agreement
Line of Credit Facility [Line Items]
Debt instrument face amount		$ 4,750,000
Stated interest rate		4.25%
Periodic principal and interest payments		$ 102,700
Long-term debt	$ 3,627,000
Level 2 | Interest Rate Swap
Line of Credit Facility [Line Items]
Notional Amount	$ 65,162,000		$ 66,046,000
Interest pay rate	4.11%
Selected LIBOR rate
Line of Credit Facility [Line Items]
Interest rate on line of credit, variable rate	1.50%
LIBOR for a fixed rate term
Line of Credit Facility [Line Items]
Interest rate on line of credit, variable rate	1.50%
Term Notes
Line of Credit Facility [Line Items]
Line of credit amount	$ 70,000,000
Interest pay rate	4.11%
Periodic payments, interest only period	2 years
Term Notes | Selected LIBOR rate
Line of Credit Facility [Line Items]
Interest rate on line of credit, variable rate	1.70%
Revolving line of credit
Line of Credit Facility [Line Items]
Line of credit amount	$ 30,000,000
Commitment fee percentage	0.10%
Number of debt covenants | covenant	3
Debt equity ratio	0.75
Debt service coverage ratio	1.25
Minimum liquid assets	$ 20,000,000