Derivatives	9 Months Ended
Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives As of September 30, 2017, we had an open position of 19,590 tonnes related to LME forward financial sales contracts, 18,240 tonnes of which are with Glencore, to fix the forward LME price (the “Forward Financial Sales Contracts”). Of these Forward Financial Sales Contracts, 16,500 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 September 30, 2017, we had an open position related to such arrangements of 6,207 tonnes settling at various dates through December 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 September 30, 2017, we had an open position of 256,200 MWh related to the power price swaps. As of September 30, 2017, we had a derivative asset and liability of $1,469 and $7,715, respectively, in the consolidated balance sheets. We recognized losses of $3,888 and $17,068 related to our derivative instruments during the three and nine months ended September 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

As of September 30, 2017, we had an open position of 19,590 tonnes related to LME forward financial sales contracts, 18,240 tonnes of which are with Glencore, to fix the forward LME price (the “Forward Financial Sales Contracts”). Of these Forward Financial Sales Contracts, 16,500 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 September 30, 2017, we had an open position related to such arrangements of 6,207 tonnes settling at various dates through December 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 September 30, 2017, we had an open position of 256,200 MWh related to the power price swaps.

As of September 30, 2017, we had a derivative asset and liability of $1,469 and $7,715, respectively, in the consolidated balance sheets. We recognized losses of $3,888 and $17,068 related to our derivative instruments during the three and nine months ended September 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.