Long-term Debt, Line of Credit and Derivatives - Provisions of the revolving line of credit and accordion (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Aug. 05, 2015
Debt Instrument [Line Items]
Repayments of debt	$ 19,031,000	$ 11,688,000
Proceeds from Lines of Credit	$ 10,000,000	$ 22,000,000
Line of Credit
Debt Instrument [Line Items]
Interest rate			4.75%
Weighted average interest rate	3.36%
Revolving line of credit
Debt Instrument [Line Items]
Fair value of amount outstanding	$ 1,500,000
Line of credit facility, remaining borrowing capacity	47,200,000
Repayments of debt	16,500,000
Proceeds from Lines of Credit	15,000,000
Revolving line of credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 50,000,000
Minimum additional borrowing amount			1,000,000
Amount over minimum additional borrowing amount, integral multiples			250,000
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	1,300,000
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	135,000,000
Fair value of amount outstanding	$ 94,000,000
Term Loan | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate, effective percentage	3.31%