Subsequent Event (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Subsequent Event
Revenues	$ 24,740,000	$ 60,387,000	$ 70,100,000	$ 161,897,000
Net income	$ 636,000	$ 1,287,000	$ 1,061,000	$ 2,823,000