Financial Instruments - Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019
Variable Interest Entity [Line Items]
Restricted cash, current	$ 29,730	[1]	$ 30,804	[1]	$ 18,419
Restricted cash, non-current	143,882	[1]	143,761	[1]	$ 31,101
Total restricted cash	173,612		174,565
Consolidated Entity, Excluding VIEs
Variable Interest Entity [Line Items]
Restricted cash, current	27,256		28,494
Restricted cash, non-current	10		10
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Restricted cash, current	2,208		2,244
Restricted cash, non-current	15,172		15,045
PPA Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Restricted cash, current	2,474		2,310
Restricted cash, non-current	$ 143,872		143,751
PPA II | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Restricted cash, non-current			108,700
PPA IIIb | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Restricted cash, non-current			$ 20,000

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