Other Receivables and Current Assets and Other Accrued Expenses and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other Receivables and Current Assets and Other Accrued Expenses and Liabilities [Abstract]
Receivables related to unrecognized revenue	$ 119,073	$ 192,154
Income taxes receivable, including overpayments and refunds	29,947	31,628
Prepaid expenses and other current assets	50,471	44,740
Total other receivables and current assets	199,491	268,522
Accrued vacation	38,396	34,132
Consumption, VAT and sales tax liabilities	26,123	45,156
Accrued expenses and other current liabilities	113,729	120,178
Total other accrued expenses and liabilities	$ 178,248	$ 199,466