Note 6 - Variable Interest Entities - Assets and Liabilities for the Company's 2015 Variable Interest Entity (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Jan. 01, 2019	Dec. 31, 2018		Dec. 31, 2017
Restricted cash and cash equivalents (primarily related to VIEs)		$ 81,937			$ 78,693
Property, plant and equipment, net		1,971,415			1,959,578
Construction-in-process		376,555			261,690
Total assets	[1]	3,250,494	[2]		3,121,350	[3]	$ 2,623,864	[3]
Accounts payable and accrued expenses		141,857		$ 113,502	116,362
Long-term debt		1,167,912
Other long-term liabilities		6,838		6,117	16,087
Total liabilities		1,725,834			1,667,651
Assets:
Restricted cash and cash equivalents		81,937			78,693		48,825
Property, plant and equipment, net		1,971,415			1,959,578
Construction-in-process		376,555			261,690
Total assets	[1]	3,250,494	[2]		3,121,350	[3]	$ 2,623,864	[3]
Liabilities:
Accounts payable and accrued expenses		141,857		113,502	116,362
Long-term debt		1,167,912
Other long-term liabilities		6,838		$ 6,117	16,087
Total liabilities		1,725,834			1,667,651
Variable Interest Entity [Member]
Construction-in-process		149,830			104,085
Assets:
Construction-in-process		149,830			104,085
Variable Interest Entity [Member] | Project Debt [Member]
Restricted cash and cash equivalents (primarily related to VIEs)		81,522
Other current assets					213,007
Property, plant and equipment, net		1,211,656			1,552,408
Construction-in-process		10,188			90,812
Other long-term assets		162,995			177,723
Total assets		1,630,747			2,109,969
Accounts payable and accrued expenses		25,361			24,245
Long-term debt		794,214			805,850
Other long-term liabilities		126,851			125,769
Total liabilities		946,426			955,864
Assets:
Restricted cash and cash equivalents					76,019
Other current assets					213,007
Property, plant and equipment, net		1,211,656			1,552,408
Construction-in-process		10,188			90,812
Other long-term assets		162,995			177,723
Total assets		1,630,747			2,109,969
Liabilities:
Accounts payable and accrued expenses		25,361			24,245
Long-term debt		794,214			805,850
Other long-term liabilities		126,851			125,769
Total liabilities		946,426			955,864
Variable Interest Entity [Member] | Power Purchase Agreement [Member]
Restricted cash and cash equivalents (primarily related to VIEs)		20
Other current assets		29,076
Assets:
Other current assets		29,076
Variable Interest Entity [Member] | Power Purchase Agreements [Member]
Other current assets					9,698
Property, plant and equipment, net		668,891			306,820
Construction-in-process		139,642			13,273
Other long-term assets		40,138			9,104
Total assets		877,767			341,199
Accounts payable and accrued expenses		13,201			2,651
Long-term debt		0			0
Other long-term liabilities		32,790			12,483
Total liabilities		45,991			15,134
Assets:
Restricted cash and cash equivalents					2,304
Other current assets					9,698
Property, plant and equipment, net		668,891			306,820
Construction-in-process		139,642			13,273
Other long-term assets		40,138			9,104
Total assets		877,767			341,199
Liabilities:
Accounts payable and accrued expenses		13,201			2,651
Long-term debt		0			0
Other long-term liabilities		32,790			12,483
Total liabilities		45,991			$ 15,134
Variable Interest Entity [Member] | Projected [Member]
Other current assets		164,386
Assets:
Other current assets		$ 164,386

[1] Electricity segment assets include goodwill in the amount of $20.1 million, $20.0 million and $7.6 as of December 31, 2019, 2018 and 2017, respectively. No goodwill is included in the Product and Energy Storage and Management Services segment assets as of December 31, 2019 and 2018. Energy Storage and Management Services segment assets as December 31, 2017 include goodwill in the amount of $13.5 million. For further information on goodwill, see Note 9 - Intangible assets and goodwill to the consolidated financial statements.

[2] Including unconsolidated investments 81,140 — — 81,140

[3] Including unconsolidated investments 34,084 — — 34,084