Long-Term Debt - Schedule of Long Term Debt (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, net	$ 72,318,000	$ 71,863,000
Note Purchase Agreement | Senior Notes
Debt Instrument [Line Items]
Face amount	75,000,000	75,000,000
Front end fees	(908,000)	(999,000)
Debt issuance costs	(1,979,000)	(2,139,000)
Back end fees	205,000	1,000
Long-term debt, net	$ 72,318,000	$ 71,863,000