Power Purchase Agreement Programs - Schedule of PPA Entities' Assets and Liabilities (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	[1]	$ 320,414	$ 220,728
Restricted cash, current	[1]	18,419	28,657
Accounts receivable	[1]	84,070	84,887
Customer financing receivable	[1]	5,717	5,594
Total current assets		639,842	672,581
Property, plant and equipment, net	[1]	475,385	481,414
Non-current portion of investment in sales-type financing leases	[1]	65,620	67,082
Restricted cash, non-current	[1]	31,101	31,100
Other long-term assets	[1]	34,386	34,792
Total assets		1,318,850	1,389,668
Current liabilities:
Accounts payable	[1]	64,425	66,889
Accrued other current liabilities	[1]	67,966	69,535
Deferred Revenue And Customer Deposits, Current	[1]	89,557	94,158
Current portion of debt		37,510	29,848
Total current liabilities		276,194	279,666
Derivative liabilities	[1]	11,166	10,128
Deferred revenue and customer deposits	[1]	201,863	241,794
Long-term portion of debt		703,568	711,433
Other long-term liabilities	[1]	58,032	55,937
Total liabilities		1,250,823	1,298,958
Variable Interest Entity, Primary Beneficiary
Current assets:
Cash and cash equivalents		9,071	5,295
Restricted cash, current		5,040	2,917
Accounts receivable		7,431	7,516
Customer financing receivable		5,717	5,594
Prepaid expenses and other current assets		3,172	4,909
Total current assets		30,431	26,231
Property, plant and equipment, net		391,121	399,060
Non-current portion of investment in sales-type financing leases		65,620	67,082
Restricted cash, non-current		27,851	27,854
Other long-term assets		2,614	2,692
Total assets		517,637	522,919
Current liabilities:
Accounts payable		426	724
Accrued other current liabilities		1,100	1,442
Deferred Revenue And Customer Deposits, Current		786	786
Current portion of debt		21,827	21,162
Total current liabilities		24,139	24,114
Derivative liabilities		5,611	3,626
Deferred revenue and customer deposits		8,502	8,696
Long-term portion of debt		317,958	323,360
Other long-term liabilities		1,938	1,798
Total liabilities		$ 358,148	$ 361,594

[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).