Subsequent Events	12 Months Ended
Dec. 31, 2012
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Public Offerings On January 30, 2013, the Company issued 37,500,000 shares of its common stock at a price per share of $6.00 (the “2013 Primary Shares”), and $150.0 million aggregate principal amount of its 5.50% Convertible Senior Notes due 2018 (the “5.50% Convertible Notes”) in separate registered public offerings. The underwriters of such offerings had the option to purchase, within a 30 days period, an additional 5,625,000 shares of the 2013 Primary Shares at a price per share of $6.00, and an additional $22.5 million aggregate principal amount of the 5.50% Convertible Notes. The purchase option on the 2013 Primary Shares was exercised on February 5, 2013 and the purchase option on the 5.50% Convertible Notes was exercised on March 1, 2013. The underwriters received a 6.00% fee in the form of an underwriter's discount for the 2013 Primary Shares. Certain officers, directors and other related parties of the Company participated in offering of the 2013 Primary Shares by purchasing 15,016,666 of the total 2013 Primary Shares issued, and $20.5 million of the 5.50% Convertible Notes. No underwriting fees were charged to the Company for the purchases of the 2013 Primary Shares by the insiders . After deducting the underwriting discounts and commissions, total net proceeds from the issuance of the 5.50% Convertible Notes were $165.6 million, and total net proceeds from the issuance of the 2013 Primary Shares were $248.6 million. The 5.50% Convertible Notes will be Molycorp's senior unsecured obligations and will pay a 5.50% interest semi-annually in arrears on February 1 and August 1 of each year, commencing on August 1, 2013. The 5.50% Convertible Notes are convertible at any time into shares of Molycorp's common stock, cash, or a combination thereof, at Molycorp's election. The conversion rate will initially be 138.8889 shares of Molycorp common stock per $1,000 principal amount of notes (equivalent to an initial conversion price of approximately $7.20 per share of Molycorp's common stock), subject to customary adjustments. The 5.50% Convertible Notes will mature on February 1, 2018, unless earlier repurchased, redeemed or converted in accordance with their terms prior to that date. Molycorp will have the right to redeem the 5.50% Convertible Notes on or after February 1, 2016 if the last reported sale price of its common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period. The Company intends to use the net proceeds received from the 2013 Primary Shares offering and the 5.50% Convertible Notes offering to fund current capital needs for capital expenditures and other cash requirements for 2013, including, without limitation, capital expenditures at its Molycorp Mountain Pass facility. Concurrently with the 2013 Primary Shares and the 5.50% Convertible Notes offerings, the Company entered into a share lending agreement with MSCS under which it has agreed to loan to MSCS up to 7,666,666 shares of common stock (the “2013 Borrowed Shares”), of which 6,333,333 shares were offered through Morgan Stanley at a price per share of $6.00 in a registered public offering. The Company entered into this share lending agreement to facilitate the 5.50% Convertible Notes offering. The Company received no proceeds from the 2013 Borrowed Shares, but only a nominal lending fee from MSCS for the use of these loaned shares. The 2013 Borrowed Shares are issued and outstanding for corporate law purposes. However, based on certain contractual undertakings of MSCS in the share lending agreement that have the effect of substantially eliminating the economic dilution that otherwise would result from the issuance of the 2013 Borrowed Shares, these loaned shares will not be considered outstanding for the purpose of computing and reporting Molycorp's earnings per share. Preferred stock dividend In February 2013, the Company declared a cash dividend of $1.375 per share on the Convertible Preferred Stock to be paid on March 1, 2013 to holders of record at the close of business on February 15, 2013.

Subsequent Events

Public Offerings

On January 30, 2013, the Company issued 37,500,000 shares of its common stock at a price per share of $6.00 (the “2013 Primary Shares”), and $150.0 million aggregate principal amount of its 5.50% Convertible Senior Notes due 2018 (the “5.50% Convertible Notes”) in separate registered public offerings. The underwriters of such offerings had the option to purchase, within a 30 days period, an additional 5,625,000 shares of the 2013 Primary Shares at a price per share of $6.00, and an additional $22.5 million aggregate principal amount of the 5.50% Convertible Notes. The purchase option on the 2013 Primary Shares was exercised on February 5, 2013 and the purchase option on the 5.50% Convertible Notes was exercised on March 1, 2013. The underwriters received a 6.00% fee in the form of an underwriter's discount for the 2013 Primary Shares. Certain officers, directors and other related parties of the Company participated in offering of the 2013 Primary Shares by purchasing 15,016,666 of the total 2013 Primary Shares issued, and $20.5 million of the 5.50% Convertible Notes. No underwriting fees were charged to the Company for the purchases of the 2013 Primary Shares by the insiders . After deducting the underwriting discounts and commissions, total net proceeds from the issuance of the 5.50% Convertible Notes were $165.6 million, and total net proceeds from the issuance of the 2013 Primary Shares were $248.6 million.

The 5.50% Convertible Notes will be Molycorp's senior unsecured obligations and will pay a 5.50% interest semi-annually in arrears on February 1 and August 1 of each year, commencing on August 1, 2013. The 5.50% Convertible Notes are convertible at any time into shares of Molycorp's common stock, cash, or a combination thereof, at Molycorp's election. The conversion rate will initially be 138.8889 shares of Molycorp common stock per $1,000 principal amount of notes (equivalent to an initial conversion price of approximately $7.20 per share of Molycorp's common stock), subject to customary adjustments. The 5.50% Convertible Notes will mature on February 1, 2018, unless earlier repurchased, redeemed or converted in accordance with their terms prior to that date. Molycorp will have the right to redeem the 5.50% Convertible Notes on or after February 1, 2016 if the last reported sale price of its common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period.

The Company intends to use the net proceeds received from the 2013 Primary Shares offering and the 5.50% Convertible Notes offering to fund current capital needs for capital expenditures and other cash requirements for 2013, including, without limitation, capital expenditures at its Molycorp Mountain Pass facility.

Concurrently with the 2013 Primary Shares and the 5.50% Convertible Notes offerings, the Company entered into a share lending agreement with MSCS under which it has agreed to loan to MSCS up to 7,666,666 shares of common stock (the “2013 Borrowed Shares”), of which 6,333,333 shares were offered through Morgan Stanley at a price per share of $6.00 in a registered public offering. The Company entered into this share lending agreement to facilitate the 5.50% Convertible Notes offering. The Company received no proceeds from the 2013 Borrowed Shares, but only a nominal lending fee from MSCS for the use of these loaned shares. The 2013 Borrowed Shares are issued and outstanding for corporate law purposes. However, based on certain contractual undertakings of MSCS in the share lending agreement that have the effect of substantially eliminating the economic dilution that otherwise would result from the issuance of the 2013 Borrowed Shares, these loaned shares will not be considered outstanding for the purpose of computing and reporting Molycorp's earnings per share.

Preferred stock dividend

In February 2013, the Company declared a cash dividend of $1.375 per share on the Convertible Preferred Stock to be paid on March 1, 2013 to holders of record at the close of business on February 15, 2013.