Financial Instruments - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	[1]	$ 226,499	$ 220,728
Cash, cash equivalents and restricted cash		357,875	280,485	$ 444,226	$ 180,612
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents		226,499	220,728
Restricted cash		131,376	59,757
Cash, cash equivalents and restricted cash		357,875	280,485
Fair Value | Cash
Debt Securities, Available-for-sale [Line Items]
Cash, cash equivalents and restricted cash		231,311	136,642
Fair Value | Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash, cash equivalents and restricted cash		$ 126,564	$ 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 - Power Purchase Agreement Programs).