Subsequent events	9 Months Ended
Sep. 30, 2014
Subsequent Events [Abstract]
Subsequent events	Subsequent events We have evaluated all subsequent events through the date the financial statements were issued. Agreement to acquire full ownership of Mt. Holly aluminum smelter On October 23, 2014, we announced that our wholly owned subsidiary, Berkeley Aluminum, Inc. ("Berkeley"), had entered into a stock purchase agreement (the "Stock Purchase Agreement") with Alumax Inc. ("Alumax"), a wholly-owned subsidiary of Alcoa Inc. ("Alcoa"), pursuant to which, upon closing, Century will acquire Alcoa’s 50.3% stake in Mt. Holly. Following the closing of the transaction, Century will own 100% of Mt. Holly. Mt. Holly, located in Berkeley County, South Carolina, employs approximately 600 people and has an annual production capacity of 229,000 tonnes of primary aluminum. Pursuant to the terms of the Stock Purchase Agreement, Berkeley has agreed to acquire all of the issued and outstanding shares of capital stock of Alumax of South Carolina Inc., a wholly owned subsidiary of Alumax for $67,500 in cash less certain amounts owed by Alumax to Mt. Holly and subject to working capital and other similar adjustments (the "Acquisition"). The Acquisition is expected to close in the fourth quarter of 2014 and is subject to customary closing conditions. Century expects to pay for the Acquisition with available cash on hand and borrowings under its revolving credit facility. Amendment to U.S. revolving credit facility On October 23, 2014, we entered into an amendment to the U.S. revolving credit facility, pursuant to which the participating banks consented to the Acquisition and revised certain covenants for a 120-day period following the Acquisition to permit the transaction. The amendment also increased Century’s letter of credit sub-facility from $80,000 to $100,000. See Note 9 Debt for additional information about the U.S. revolving credit facility.

Subsequent events

We have evaluated all subsequent events through the date the financial statements were issued.

Agreement to acquire full ownership of Mt. Holly aluminum smelter

On October 23, 2014, we announced that our wholly owned subsidiary, Berkeley Aluminum, Inc. ("Berkeley"), had entered into a stock purchase agreement (the "Stock Purchase Agreement") with Alumax Inc. ("Alumax"), a wholly-owned subsidiary of Alcoa Inc. ("Alcoa"), pursuant to which, upon closing, Century will acquire Alcoa’s 50.3% stake in Mt. Holly. Following the closing of the transaction, Century will own 100% of Mt. Holly. Mt. Holly, located in Berkeley County, South Carolina, employs approximately 600 people and has an annual production capacity of 229,000 tonnes of primary aluminum.

Pursuant to the terms of the Stock Purchase Agreement, Berkeley has agreed to acquire all of the issued and outstanding shares of capital stock of Alumax of South Carolina Inc., a wholly owned subsidiary of Alumax for $67,500 in cash less certain amounts owed by Alumax to Mt. Holly and subject to working capital and other similar adjustments (the "Acquisition"). The Acquisition is expected to close in the fourth quarter of 2014 and is subject to customary closing conditions. Century expects to pay for the Acquisition with available cash on hand and borrowings under its revolving credit facility.

Amendment to U.S. revolving credit facility

On October 23, 2014, we entered into an amendment to the U.S. revolving credit facility, pursuant to which the participating banks consented to the Acquisition and revised certain covenants for a 120-day period following the Acquisition to permit the transaction. The amendment also increased Century’s letter of credit sub-facility from $80,000 to $100,000. See Note 9 Debt for additional information about the U.S. revolving credit facility.