Derivatives	3 Months Ended
Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives As of March 31, 2018, we had an open position of 3,090 tonnes related to LME forward financial sales contracts, all of which are with Glencore, to fix the forward LME price (the “forward financial sales contracts”). These forward financial sales contracts are expected to settle monthly, on a ratable basis, between November 1, 2019 and December 31, 2020. We also have financial contracts with various counterparties, including 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 March 31, 2018, we had open positions related to such arrangements of 11,337 tonnes settling at various dates through June 2019. In 2017, we entered into financial contracts to fix the forward price of approximately 4% of Grundartangi's total power requirements 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 March 31, 2018, we had an open position of 256,200 MWh related to the power price swaps. As of March 31, 2018, we had a derivative asset and liability of $2.0 million and $1.1 million, respectively, in the consolidated balance sheets. We recognized gains of $0.7 million related to our derivative instruments during the three months ended March 31, 2018 in the consolidated statements of operations, a portion of which related to transactions with Glencore. At December 31, 2017, we had a derivative asset and liability of $1.7 million and $1.2 million, respectively, in the consolidated balance sheets. We recognized losses of $16.1 million related to our derivative instruments during the three months ended March 31, 2017, in the consolidated statements of operations, substantially all of which related to transactions with Glencore.

Derivatives

As of March 31, 2018, we had an open position of 3,090 tonnes related to LME forward financial sales contracts, all of which are with Glencore, to fix the forward LME price (the “forward financial sales contracts”). These forward financial sales contracts are expected to settle monthly, on a ratable basis, between November 1, 2019 and December 31, 2020. We also have financial contracts with various counterparties, including 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 March 31, 2018, we had open positions related to such arrangements of 11,337 tonnes settling at various dates through June 2019.

In 2017, we entered into financial contracts to fix the forward price of approximately 4% of Grundartangi's total power requirements 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 March 31, 2018, we had an open position of 256,200 MWh related to the power price swaps.

As of March 31, 2018, we had a derivative asset and liability of $2.0 million and $1.1 million, respectively, in the consolidated balance sheets. We recognized gains of $0.7 million related to our derivative instruments during the three months ended March 31, 2018 in the consolidated statements of operations, a portion of which related to transactions with Glencore.

At December 31, 2017, we had a derivative asset and liability of $1.7 million and $1.2 million, respectively, in the consolidated balance sheets. We recognized losses of $16.1 million related to our derivative instruments during the three months ended March 31, 2017, in the consolidated statements of operations, substantially all of which related to transactions with Glencore.