Financial Instruments - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	[1]	$ 320,414	$ 220,728
Cash, cash equivalents and restricted cash		369,934	280,485	$ 143,592	$ 180,612
Amortized Cost
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents		320,414
Restricted cash		49,520
Cash, cash equivalents and restricted cash		369,934
Amortized Cost | Cash
Debt Securities, Available-for-sale [Line Items]
Cash, cash equivalents and restricted cash		152,676
Amortized Cost | Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash, cash equivalents and restricted cash		$ 217,258
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents			220,728
Restricted cash			59,757
Cash, cash equivalents and restricted cash			280,485
Fair Value | Cash
Debt Securities, Available-for-sale [Line Items]
Cash, cash equivalents and restricted cash			136,642
Fair Value | Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash, cash equivalents and restricted cash			$ 143,843

[1] We have variable interest entities which represent a portion of the consolidated balances are recorded within the "Cash and cash equivalents," "Restricted cash," "Accounts receivable," "Customer financing receivable," "Prepaid expenses and other current assets," "Property and equipment, net," "Customer financing receivable, non-current," "Restricted cash, non-current," "Other long-term assets," "Accounts payable," "Accrued other current liabilities," "Deferred revenue and customer deposits," "Current portion of non-recourse debt from related parties," "Derivative liabilities, net of current portion," "Deferred revenue and customer deposits, net of current portion," "Long-term portion of non-recourse debt," and "Other long-term liabilities" financial statement line items in the Condensed Consolidated Balance Sheets (see Note 12).