Power Purchase Agreement Programs - Schedule of Consolidated Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Current assets	$ 672,581	$ 419,981
Long-term assets	717,087	801,006
Total assets	1,389,668	1,220,987
Current liabilities	249,818	251,148
Current portion of debt	29,848	20,136
Long-term liabilities	307,859	529,135
Long-term portion of debt	711,433	921,205
Total liabilities	1,298,958	1,721,624
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Current assets	26,231	36,772
Long-term assets	496,688	533,656
Total assets	522,919	570,428
Current liabilities	2,952	3,684
Current portion of debt	21,162	18,446
Long-term liabilities	14,120	15,768
Long-term portion of debt	323,360	342,050
Total liabilities	361,594	379,948
Bloom
Variable Interest Entity [Line Items]
Current assets	646,350	383,209
Long-term assets	220,399	267,350
Total assets	866,749	650,559
Current liabilities	246,866	247,464
Current portion of debt	8,686	1,690
Long-term liabilities	293,739	513,367
Long-term portion of debt	388,073	579,155
Total liabilities	$ 937,364	$ 1,341,676