Long-term Debt, Line of Credit and Derivatives - Provisions of the revolving line of credit and accordion (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Aug. 05, 2015
Debt Instrument [Line Items]
Repayments of debt	$ 10,750,000	$ 8,375,000
Proceeds from Lines of Credit	11,000,000	$ 0
Line of Credit
Debt Instrument [Line Items]
Weighted average interest rate		4.92%
Revolving line of credit
Debt Instrument [Line Items]
Fair value of amount outstanding	23,000,000
Line of credit facility, remaining borrowing capacity	41,200,000
Repayments of debt	10,000,000
Proceeds from Lines of Credit	$ 11,000,000
Revolving line of credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 65,000,000	$ 100,000,000
Minimum additional borrowing amount				1,000,000
Amount over minimum additional borrowing amount, integral multiples				250,000
Stated interest rate	5.25%
Revolving line of credit | Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				20,000,000
Letters of credit outstanding, amount	$ 800,000
Revolving line of credit | Bridge Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				5,000,000
Minimum additional borrowing amount				250,000
Amount over minimum additional borrowing amount, integral multiples				$ 50,000
Term Loan | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 60,000,000
Fair value of amount outstanding	$ 57,800,000
Term Loan | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate, effective percentage	5.25%