Balance Sheet Components Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Tax related receivables	$ 54,059	$ 36,794
Current promissory note receivable	26,699	0
Other current receivables	18,826	6,511
Prepaid software and maintenance	16,682	5,938
Other prepaid expenses and current assets	18,968	23,227
Total prepaid expenses and other current assets	$ 135,234	$ 72,470