Fair Value (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value, Assets and Liabilities Measured on Recurring Basis

The tables below sets forth, by level, the Company’s 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, 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 other current liabilities	$	1,331	$	—	$	—	$	1,331
Derivatives:
Natural gas fixed price forward contracts	—		—		9,729		9,729
Interest rate swap agreements	—		3,630		—		3,630
	$	1,331	$	3,630	$	9,729	$	14,690



	Fair Value Measured at Reporting Date Using
December 31, 2017	Level 1		Level 2		Level 3		Total

Assets
Cash equivalents:
Money market funds	$	79,256	$	—	$	—	$	79,256
Short-term investments	26,816		—		—		26,816
Interest rate swap agreements	—		52		—		52
	$	106,072	$	52	$	—	$	106,124
Liabilities
Derivatives:
Natural gas fixed price forward contracts	$	—	$	—	$	15,368	$	15,368
Embedded derivative on 6% promissory notes	—		—		140,771		140,771
Interest rate swap agreements	—		5,905		—		5,905
Stock warrants:
Preferred stock warrants	—		—		9,825		9,825
Accrued other long term liabilities	—		5,149		—		5,149
	$	—	$	11,054	$	165,964	$	177,018

Schedule of Natural Gas Forward Contracts

The following table provides the fair value of the Company’s natural gas fixed price contracts (dollars in thousands):



	December 31,
	2018			2017
	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)	3,096		$9,729	4,332		$15,368

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			Total

Balances at December 31, 2016	$	18,585		$	12,885		$	115,807		$	147,277
Settlement of natural gas fixed price forward contracts	(4,248		)	—			—			(4,248		)
Embedded derivative on notes	—			—			6,804			6,804
Changes in fair value	1,031			(3,060		)	18,160			16,131
Balances at December 31, 2017	$	15,368		$	9,825		$	140,771		$	165,964
Settlement of natural gas fixed price forward contracts	(3,412		)	—			—			(3,412		)
Embedded derivative on notes	—			—			5,533			5,533
Changes in fair value	(2,227		)	(8,943		)	30,904			19,734
Reclassification of preferred stock warrants liability to common stock warrants and derivative liability into additional paid-in-capital	—			(882		)	(177,208		)	(178,090		)
Balances at December 31, 2018	$	9,729		$	—		$	—		$	9,729

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, 2018				December 31, 2017
	Net Carrying Value		Fair Value		Net Carrying Value		Fair Value

Customer receivables:
Customer financing receivables	$	72,676	$	51,541	$	77,885	$	55,255
Debt instruments:
Recourse
LIBOR + 4% term loan due November 2020	3,214		3,311		4,887		5,148
5% convertible promissory note due December 2020	34,706		31,546		—		—
8% convertible promissory notes due December 2018	—		—		244,717		211,000
6% convertible promissory notes due December 2020	263,284		353,368		236,724		219,094
10% notes due July 2024	95,555		99,260		94,517		106,124
Non-recourse
5.22% senior secured notes due March 2025	78,566		80,838		89,564		95,114
7.5% term loan due September 2028	36,319		39,892		36,940		46,713
LIBOR + 5.25% term loan due October 2020	23,916		25,441		24,364		27,206
6.07% senior secured notes due March 2030	82,337		85,917		84,032		93,264
LIBOR + 2.5% term loan due December 2021	123,384		123,040		125,596		131,817