Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Fair Value of Derivatives Held

The fair values of derivative instruments held as of December 31, 2017 and 2016 are shown below:

		December 31,
	Balance sheet location	2017		2016
Asset derivatives:
Derivatives designated as cash flow hedges:
Natural gas swaps	Current assets	$	—	$	573
Interest rate caps	Current assets	44		—
Natural gas swaps	Other long-term assets	—		58
Interest rate caps	Other long-term assets	999		5,803
Total asset derivatives		$	1,043	$	6,434
Liability derivatives:
Derivatives designated as cash flow hedges:
Natural gas swaps	Current liabilities	$	318	$	—
Natural gas swaps	Other long-term liabilities	130		—
Total liability derivatives		$	448	$	—

Effect of Derivative Instruments Designated as Hedges on Other Comprehensive Income

The following table shows the effect of the Company’s derivative instruments designated as hedges on other comprehensive income (loss) (“OCI”) and the statements of operations for the years ended December 31, 2017 and 2016:

		December 31,
	Location in earnings	2017			2016
Derivatives designated as cash flow hedges:
AOCI derivative gain at beginning of year		$	4,881		$	—
Effective portion of changes in fair value recognized in OCI:
Interest rate caps		(4,760		)	4,250
Natural gas swaps		(1,300		)	(802		)
Amount of loss reclassified from OCI to earnings:
Interest rate caps	Interest expense	40			—
Natural gas swaps	Cost of goods sold	222			1,433
AOCI derivative gain (loss) at end of year		$	(917	)	$	4,881