Basis of Presentation - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of January 1	$ 3,332
Provision for expected credit losses	5,178
Amounts written off charged against the allowance	(1,333)
Balance as of September 30	8,511	$ 3,332
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of January 1	$ 1,334
Balance as of September 30		$ 1,334