Note 9 - Fair Value of Financial Instruments - Fair Value Measurements, Recorded (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Total assets at fair value	$ 32	$ 382
Liabilities:
Embedded customer derivative	32
Total liabilities recorded at fair value	32	387
Embedded customer derivatives		382
Assets:
Total assets at fair value	32	382
Metal Swaps [Member]
Total assets at fair value	32	382
Assets:
Total assets at fair value	32	382
Interest Rate Swap [Member]
Liabilities:
Derivative liabilities		5
Fair Value, Inputs, Level 1 [Member]
Total assets at fair value
Liabilities:
Embedded customer derivative
Total liabilities recorded at fair value
Embedded customer derivatives
Assets:
Total assets at fair value
Fair Value, Inputs, Level 1 [Member] | Metal Swaps [Member]
Total assets at fair value
Assets:
Total assets at fair value
Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Liabilities:
Derivative liabilities
Fair Value, Inputs, Level 2 [Member]
Total assets at fair value	32	382
Liabilities:
Embedded customer derivative	32
Total liabilities recorded at fair value	32	387
Embedded customer derivatives		382
Assets:
Total assets at fair value	32	382
Fair Value, Inputs, Level 2 [Member] | Metal Swaps [Member]
Total assets at fair value	32	382
Assets:
Total assets at fair value	32	382
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Liabilities:
Derivative liabilities		5
Fair Value, Inputs, Level 3 [Member]
Total assets at fair value
Liabilities:
Embedded customer derivative
Total liabilities recorded at fair value
Embedded customer derivatives
Assets:
Total assets at fair value
Fair Value, Inputs, Level 3 [Member] | Metal Swaps [Member]
Total assets at fair value
Assets:
Total assets at fair value
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Liabilities:
Derivative liabilities