Line-of-Credit and Long-term Debt - Additional Information (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2013 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Oct. 13, 2014 USD ($)
Line of Credit Facility [Line Items]
Interest rate swap, fixed rate		4.11%
Long-term debt		$ 69,959,000
Interest Rate Swap | Other Liabilities | Level 2
Line of Credit Facility [Line Items]
Notional Amount		$ 66,046,000
Interest rate swap, fixed rate		4.11%
Revolving line of credit
Line of Credit Facility [Line Items]
Total short-term and long-term debt		$ 0	$ 7,700,000
Promissory Note
Line of Credit Facility [Line Items]
Face amount	$ 4,750,000
Stated percentage	4.25%
Monthly principal and interest payments	$ 102,700
Long-term debt		$ 3,695,000
Term loan
Line of Credit Facility [Line Items]
Line of credit amount				$ 70,000,000
Interest only payment period		2 years
Term loan | Selected LIBOR rate
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.17%
Revolving line of credit
Line of Credit Facility [Line Items]
Line of credit amount				$ 30,000,000
Commitment fee percentage		0.01%
Liquid assets		$ 20,000,000
Revolving line of credit | Maximum
Line of Credit Facility [Line Items]
Total liabilities divided by tangible net worth, not greater than		0.75
Revolving line of credit | Minimum
Line of Credit Facility [Line Items]
Debt service coverage ratio, not less than		1.25
Revolving line of credit | Selected LIBOR rate
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.50%
Revolving line of credit | LIBOR for a fixed rate term
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.50%