Summary of Significant Accounting Policies - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Trade receivables	$ 75,977	$ 60,121
Less: allowance for doubtful accounts	(4,654)	(7,562)	$ (4,404)	$ (1,940)
Accounts receivable, net of allowance	$ 71,323	$ 52,559