Line of Credit (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Line of Credit Facility [Line Items]
Amount outstanding under line of credit	$ 46,000,000		$ 46,000,000		$ 20,000,000
Interest expense on borrowings	$ 200,000	$ 400,000	$ 300,000	$ 1,100,000
Line of credit | US Bank
Line of Credit Facility [Line Items]
Effective interest rate	1.35%		1.35%		1.39%
Line of credit | US Bank | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.25%
Line of credit | US Bank | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.75%
Line of credit | US Bank | Base rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.00%
Line of credit | US Bank | Base rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Line of credit | US Bank | Enson
Line of Credit Facility [Line Items]
Ownership interest used to secure obligations	65.00%		65.00%
Line of credit | Second Amended Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 125,000,000.0		$ 125,000,000.0
Commitment fees			0
Letter of credit
Line of Credit Facility [Line Items]
Letter of credit outstanding amount	$ 2,700,000		$ 2,700,000		$ 2,700,000