Accounts Receivable, Net - Schedule of Accounts Receivables Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade accounts receivable	$ 167,575	$ 176,375
Unbilled revenue, at net realizable value	63,494	60,035
Total accounts receivable	231,069	236,410
Allowance for doubtful accounts	(14,894)	(14,379)	$ (13,389)	$ (13,827)
Accounts receivable, net	$ 216,175	$ 222,031