Income Taxes (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, 2018	Dec. 31, 2017
Effective tax rates reconciliation
Statutory federal income tax rate (as a percent)			21.00%	21.00%	21.00%	35.00%
Annual income tax rate (as a percent)			37.40%	34.60%
Effective tax rate relates to excess foreign tax credits			10.30%
Annual effective rate relates to the required valuation allowance (as a percent)			10.30%
Income tax expense	$ 4,664	$ 3,743	$ 5,873	$ 9,942
U.S.
Effective tax rates reconciliation
Annual income tax rate (as a percent)			27.10%