Other Receivables and Current Assets, Other Accrued Expenses and Liabilities, and Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Receivables and Current Assets, Other Accrued Expenses and Liabilities, and Other Long-Term Liabilities [Abstract]
Receivables related to unrecognized revenue	$ 145,097	$ 177,679
Income taxes receivable, including overpayments and refunds	53,156	26,672
Prepaid expenses and other current assets	43,907	45,268
Total other receivables and current assets	242,160	249,619
Accrued vacation	32,866	24,336
Consumption, VAT and sales tax liabilities	23,814	36,398
Accrued expenses and other current liabilities	86,176	82,213
Total other accrued expenses and liabilities	142,856	142,947
Uncertain tax positions	69,906	64,375
Other long-term liabilities	35,500	32,051
Total other long-term liabilities	$ 105,406	$ 96,426