Note 12 - Derivatives (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Derivative Assets and Liabilities at Fair Value [Table Text Block]

December 31,		Fair Value of Derivative Assets
(dollars in thousands)	Balance Sheet Location	2019		2018
Interest rate swaps	Prepaid and other current assets	$	—	$	1,425
Natural gas contracts	Prepaid and other current assets		—		226
Natural gas contracts	Other assets		—		39
Total derivative assets		$	—	$	1,690
		Fair Value of Derivative Liabilities
Interest rate swaps	Accrued liabilities	$	2,931	$	—
Interest rate swaps	Other long-term liabilities		11,632		5,713
Natural gas contracts	Accrued liabilities		836		—
Natural gas contracts	Other long-term liabilities		3		—
Total derivative liabilities		$	15,402	$	5,713

Schedule of Derivative Instruments [Table Text Block]

Year ended December 31,
(dollars in thousands)	2019			2018
Natural gas contracts	$	(651	)	$	426
Interest rate swaps		993			159
Total	$	342		$	585

Derivative Instruments, Gain (Loss) [Table Text Block]

Year ended December 31,
(dollars in thousands)	Location	2019			2018
Derivative gain (loss) recognized in OCI:
Natural gas contracts	OCI	$	(1,755	)	$	1,194
Interest rate swaps	OCI		(9,375	)		(4,436	)
Total		$	(11,130	)	$	(3,242	)
Derivative gain (loss) reclassified from accumulated OCI to current earnings:
Natural gas contracts	Cost of Sales	$	(651	)	$	426
Interest rate swaps	Interest expense		901			285
Total		$	250		$	711

Interest Rate Swap [Member]

Notes Tables

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

Swap execution date	Effective date	Expiration date	Notional amount	Fixed swap rate
April 1, 2015	January 11, 2016	January 9, 2020	$220.0 million		4.85	%
September 24, 2018	January 9, 2020	January 9, 2025	$200.0 million		6.19	%	(1)

Natural Gas Contracts [Member]

Notes Tables

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

		Notional Amounts
Derivative Types	Unit of Measure	December 31, 2019		December 31, 2018
Natural gas contracts	Millions of British Thermal Units (MMBTUs)		2,460,000		3,150,000