Power Purchase Agreement Programs - Schedule of Consolidated Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Current assets	$ 639,842	$ 672,581
Long-term assets	679,008	717,087
Total assets	1,318,850	1,389,668
Current liabilities	238,684	249,818
Current portion of debt	37,510	29,848
Long-term liabilities	271,061	307,859
Long-term portion of debt	703,568	711,433
Total liabilities	1,250,823	1,298,958
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Current assets	30,431	26,231
Long-term assets	487,206	496,688
Total assets	517,637	522,919
Current liabilities	2,312	2,952
Current portion of debt	21,827	21,162
Long-term liabilities	16,051	14,120
Long-term portion of debt	317,958	323,360
Total liabilities	358,148	361,594
Bloom
Variable Interest Entity [Line Items]
Current assets	609,411	646,350
Long-term assets	191,802	220,399
Total assets	801,213	866,749
Current liabilities	236,372	246,866
Current portion of debt	15,683	8,686
Long-term liabilities	255,010	293,739
Long-term portion of debt	385,610	388,073
Total liabilities	$ 892,675	$ 937,364