Derivatives	6 Months Ended
Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives As of June 30, 2017, we had an open position of 36,090 tonnes related to LME forward financial sales contracts, 33,390 tonnes of which are with Glencore, to fix the forward LME price (the “Forward Financial Sales Contracts”). Of these Forward Financial Sales Contracts, 33,000 tonnes settle monthly, on a ratable basis, through December 31, 2017, with the remainder expected to settle between November 1, 2019 and December 31, 2020. We also have financial contracts with Glencore to offset fixed price sales arrangements with certain of our customers (the “fixed for floating swaps”) to remain exposed to the LME price. As of June 30, 2017, we had an open position related to such arrangements of 7,386 tonnes settling at various dates through August 2018. We have also entered into financial contracts to fix the forward price of approximately 4% of power purchases at Grundartangi for the period November 1, 2019 through December 31, 2020 (the “power price swaps”). The power price swaps are not designated as cash flow hedges. As of June 30, 2017, we had an open position of 256,200 MWh related to the power price swaps. As of June 30, 2017, we had a derivative asset and liability of $354 and $7,539, respectively, in the consolidated balance sheets. We recognized a gain of $2,957 and a loss of $13,180 related to our derivative instruments during the three and six months ended June 30, 2017, respectively, in the consolidated statements of operations, substantially all of which related to transactions with Glencore. The impact of the derivative instruments on the consolidated balance sheets and consolidated statements of operations was not material for the corresponding prior periods presented.

Derivatives

6 Months Ended

Jun. 30, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

As of June 30, 2017, we had an open position of 36,090 tonnes related to LME forward financial sales contracts, 33,390 tonnes of which are with Glencore, to fix the forward LME price (the “Forward Financial Sales Contracts”). Of these Forward Financial Sales Contracts, 33,000 tonnes settle monthly, on a ratable basis, through December 31, 2017, with the remainder expected to settle between November 1, 2019 and December 31, 2020. We also have financial contracts with Glencore to offset fixed price sales arrangements with certain of our customers (the “fixed for floating swaps”) to remain exposed to the LME price. As of June 30, 2017, we had an open position related to such arrangements of 7,386 tonnes settling at various dates through August 2018.

We have also entered into financial contracts to fix the forward price of approximately 4% of power purchases at Grundartangi for the period November 1, 2019 through December 31, 2020 (the “power price swaps”). The power price swaps are not designated as cash flow hedges. As of June 30, 2017, we had an open position of 256,200 MWh related to the power price swaps.

As of June 30, 2017, we had a derivative asset and liability of $354 and $7,539, respectively, in the consolidated balance sheets. We recognized a gain of $2,957 and a loss of $13,180 related to our derivative instruments during the three and six months ended June 30, 2017, respectively, in the consolidated statements of operations, substantially all of which related to transactions with Glencore. The impact of the derivative instruments on the consolidated balance sheets and consolidated statements of operations was not material for the corresponding prior periods presented.