Fair Value (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value, Assets and Liabilities Measured on Recurring Basis

The tables below set forth, by level, our financial assets that were accounted for at fair value for the respective periods. The table does not include assets and liabilities that are measured at historical cost or any basis other than fair value (in thousands):



	Fair Value Measured at Reporting Date Using
December 31, 2019	Level 1		Level 2		Level 3		Total

Assets
Cash equivalents:
Money market funds	$	276,615	$	—	$	—	$	276,615
Interest rate swap agreements	—		3		—		3
	$	276,615	$	3	$	—	$	276,618
Liabilities
Accrued expenses and other current liabilities	$	996	$	—	$	—	$	996
Derivatives:
Natural gas fixed price forward contracts	—		—		6,968		6,968
Embedded EPP derivatives	—		—		6,176		6,176
Interest rate swap agreements	—		9,241		—		9,241
	$	996	$	9,241	$	13,144	$	23,381



	Fair Value Measured at Reporting Date Using
December 31, 2018	Level 1		Level 2		Level 3		Total

Assets
Cash equivalents:
Money market funds	$	143,843	$	—	$	—	$	143,843
Short-term investments	104,350		—		—		104,350
Interest rate swap agreements	—		82		—		82
	$	248,193	$	82	$	—	$	248,275
Liabilities
Accrued expenses and other current liabilities	$	1,331	$	—	$	—	$	1,331
Derivatives:
Natural gas fixed price forward contracts	—		—		9,729		9,729
Embedded EPP derivatives	—		—		4,015		4,015
Interest rate swap agreements	—		3,630		—		3,630
	$	1,331	$	3,630	$	13,744	$	18,705

Schedule of Natural Gas Forward Contracts

The following table provides the number and fair value of our natural gas fixed price forward contracts (in thousands):



	December 31,
	2019			2018
	Number of Contracts (MMBTU)²	Fair Value		Number of Contracts (MMBTU)²	Fair Value

Liabilities¹
Natural gas fixed price forward contracts (not under hedging relationships)	1,991	$	6,968	3,096	$	9,729

¹ Recorded in current liabilities and derivative liabilities in the consolidated balance sheets.
² One MMBTU is a traditional unit of energy used to describe the heat value (energy content) of fuels.

Change in Level 3 Financial Liabilities

The changes in the Level 3 financial assets were as follows (in thousands):



	Natural Gas Fixed Price Forward Contracts			Preferred Stock Warrants			Embedded Derivative Liability			Embedded EPP Derivative			Total
Balances at December 31, 2017	$	15,368		$	9,825		$	140,771		$	4,217		$	170,181
Settlement of natural gas fixed price forward contracts	(3,412		)	—			—			0			(3,412		)
Embedded derivative on notes and sales contracts	—			—			6,288			3			6,291
Changes in fair value	(2,227		)	(8,943		)	30,904			(205		)	19,529
Reclassification of preferred stock warrants liability to common stock warrants and derivative liability into additional paid-in-capital	—			(882		)	(177,963		)	—			(178,845		)
Balances at December 31, 2018	9,729			—			—			4,015			13,744
Settlement of natural gas fixed price forward contracts	(3,605		)	—			—			—			(3,605		)
Changes in fair value	844			—			—			2,161			3,005
Balances at December 31, 2019	$	6,968		$	—		$	—		$	6,176		$	13,144

Schedule of Fair Values and Carrying Values of Customer Receivables and Debt Instruments

The following table presents the estimated fair values and carrying values of customer receivables and debt instruments (in thousands):



	December 31, 2019				December 31, 2018
	Net Carrying Value		Fair Value		Net Carrying Value		Fair Value

Customer receivables:
Customer financing receivables	$	55,855	$	44,002	$	72,676	$	51,541
Debt instruments:
Recourse
LIBOR + 4% term loan due November 2020	1,536		1,590		3,214		3,311
5% convertible promissory note due December 2020	36,482		32,070		34,706		31,546
6% convertible promissory notes due December 2020	273,410		302,047		263,284		353,368
10% notes due July 2024	89,962		97,512		95,555		99,260
Non-recourse
5.22% senior secured notes due March 2025	—		—		78,566		80,838
7.5% term loan due September 2028	34,969		41,108		36,319		39,892
LIBOR + 5.25% term loan due October 2020	—		—		23,916		25,441
6.07% senior secured notes due March 2030	80,016		87,618		82,337		85,917
LIBOR + 2.5% term loan due December 2021	120,436		120,510		123,384		123,040