Summary of Significant Accounting Policies - Accounts Receivable, Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts:
Beginning balance	$ 982	$ 359	$ 0
Add: Reserves	386	1,052	0
Less: Write-offs	(80)	(429)	359
Ending balance	$ 1,288	$ 982	$ 359