Long-term Debt and Line of Credit - Provisions of Revolving Line of Credit (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Repayments of Debt	$ 48,204,000	$ 70,210,000	$ 48,111,000
Proceeds from lines of credit	$ 10,000,000	$ 63,000,000	$ 39,861,000
Line of Credit
Debt Instrument [Line Items]
Weighted average interest rate	3.11%
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50,000,000.0
Minimum borrowing increment amount	1,000,000.0
Increment borrowing multiple for amounts borrowed in excess of minimum borrowing amount	250,000
Remaining borrowing capacity	43,300,000
Repayments of Debt	41,000,000.0
Decrease in debt balance	31,000,000.0
Proceeds from lines of credit	10,000,000.0
Revolving Credit Facility | Line of Credit | Base Rate
Debt Instrument [Line Items]
Amount outstanding	$ 5,000,000.0
Weighted average interest rate	4.50%
Letter of Credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 20,000,000.0
Letters of credit outstanding	1,700,000
Bridge Loan | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	5,000,000.0
Minimum borrowing increment amount	250,000
Increment borrowing multiple for amounts borrowed in excess of minimum borrowing amount	$ 50,000