Power Purchase Agreement Programs - Schedule of Consolidated Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Current assets	$ 592,284	$ 672,581
Long-term assets	630,295	717,087
Total assets	1,222,579	1,389,668
Current liabilities	312,863	249,818
Current portion of debt	26,224	29,848
Long-term liabilities	252,717	307,859
Long-term portion of debt	641,983	711,433
Total liabilities	1,233,787	1,298,958
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Current assets	33,826	26,231
Long-term assets	453,097	496,688
Total assets	486,923	522,919
Current liabilities	40,257	2,952
Current portion of debt	10,544	21,162
Long-term liabilities	18,837	14,120
Long-term portion of debt	251,826	323,360
Total liabilities	321,464	361,594
Bloom
Variable Interest Entity [Line Items]
Current assets	558,458	646,350
Long-term assets	177,198	220,399
Total assets	735,656	866,749
Current liabilities	272,606	246,866
Current portion of debt	15,680	8,686
Long-term liabilities	233,880	293,739
Long-term portion of debt	390,157	388,073
Total liabilities	$ 912,323	$ 937,364