Line of Credit and Long-term Debt - Additional Information (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2013 USD ($)	Dec. 31, 2019 USD ($) covenant	Sep. 30, 2019 USD ($)	Aug. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Line of Credit Facility [Line Items]
Long-term debt		$ 61,897,000
Interest pay rate				4.16%
Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit amount			$ 35,000,000	$ 30,000,000
RLC outstanding balance		$ 0			$ 0
Commitment fee percentage		0.01%
Number of covenants | covenant		3
Debt equity ratio		0.75
Debt service coverage ratio		1.25
Liquid assets		$ 20,000,000
Revolving credit facility | Selected LIBOR rate
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.50%
Revolving credit facility | LIBOR for a fixed rate term
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.50%
Medium-term notes
Line of Credit Facility [Line Items]
Long-term debt		$ 58,768,000			$ 62,483,000
Medium-term notes | Selected LIBOR rate
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.17%
Promissory note
Line of Credit Facility [Line Items]
Long-term debt		$ 3,129,000
Face amount	$ 4,750,000
Stated percentage	4.25%
Monthly principal and interest payments	$ 36,000