Power Purchase Agreement Programs - Schedule of PPA Entities' Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents		$ 202,823	[1]	$ 226,499	$ 308,009	$ 320,414	$ 220,728	$ 220,728	[1]	$ 395,516	$ 91,596	$ 88,227
Restricted cash, current		30,804	[1]	14,486	23,706	18,419	28,657	28,657	[1]	17,931	25,860	22,998
Accounts receivable		37,828	[1]	26,353	40,038	85,647	89,779	88,784	[1]	45,261	40,442	61,996
Customer financing receivable		5,108	[1]	5,919	5,817	5,717	5,594	5,594	[1]	5,496	5,398	5,303
Total current assets		472,707		475,548	591,249	633,052	665,069	663,934		688,158	368,757	365,053
Property, plant and equipment, net		607,059	[1]	627,385	641,259	711,631	716,751	716,751	[1]	698,123	697,344	702,228
Non-current portion of investment in sales-type financing leases		50,747	[1]	62,615	64,146	65,620	67,082	67,082	[1]	68,535	69,963	71,337
Restricted cash, non-current		143,761	[1]	116,890	39,351	31,101	31,100	31,100	[1]	30,779	32,416	32,367
Other long-term assets		41,652	[1]	70,951	72,836	45,447	45,354	42,882	[1]	44,397	45,241	43,179
Total assets		1,322,591		1,357,113	1,412,687	1,488,784	1,525,401	1,521,794		1,530,037	1,213,781	1,214,217
Current liabilities:
Accounts payable		55,579	[1]	81,060	61,427	64,425	66,889	66,889	[1]	59,818	53,798	47,755
Accrued other current liabilities		70,284	[1]	79,616	105,393	64,073	66,838	66,838	[1]	63,986	49,932	53,654
Deferred revenue and customer deposits	[1]	89,192					72,285	67,632
Current portion of debt		337,583						29,848
Total current liabilities		573,964		288,670	332,049	264,133	260,924	257,303		243,556	220,869	220,970
Derivative liabilities		17,551	[1]	20,284	18,175	15,722	14,143	14,143	[1]	13,658	192,416	168,071
Deferred revenue and customer deposits		125,529	[1]	122,276	110,750	103,751	105,290	87,308	[1]	89,204	88,630	89,501
Long-term portion of debt		299,229						711,433
Other long-term liabilities		28,013		28,852	29,979	28,970	26,196	26,196		18,437	21,564	21,753
Total liabilities		1,490,451		$ 1,494,162	$ 1,533,014	$ 1,510,181	$ 1,503,636	1,482,033		$ 1,458,998	$ 1,812,698	$ 1,753,873
Variable Interest Entity, Primary Beneficiary
Current assets:
Cash and cash equivalents		1,894						5,295
Restricted cash, current		2,244						2,917
Accounts receivable		4,194						7,516
Customer financing receivable		5,108						5,594
Prepaid expenses and other current assets		3,587						4,909
Total current assets		17,027						26,231
Property, plant and equipment, net		275,481						399,060
Non-current portion of investment in sales-type financing leases		50,747						67,082
Restricted cash, non-current		15,045						27,854
Other long-term assets		607						2,692
Total assets		358,907						522,919
Current liabilities:
Accounts payable		0						724
Accrued other current liabilities		1,391						1,442
Deferred revenue and customer deposits		662						786
Current portion of debt		12,155						21,162
Total current liabilities		14,208						24,114
Derivative liabilities		8,459						3,626
Deferred revenue and customer deposits		6,735						8,696
Long-term portion of debt		223,267						323,360
Other long-term liabilities		2,355						1,798
Total liabilities		$ 255,024						$ 361,594

[1] We have variable interest entities which represent a portion of the consolidated balances are recorded within these financial statement line items in the Consolidated Balance Sheets (see Note 13, Power Purchase Agreement Programs).