Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Components of Net Periodic Benefit Cost
Service cost	$ 313	$ 300	$ 940	$ 749	$ 998
Interest cost	326	348	979	1,045	$ 1,393
Net loss	135	53	405	158
Net periodic pension cost	$ 774	$ 701	$ 2,324	$ 1,952