Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Share data	3 Months Ended				6 Months Ended				37 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011
Consolidated Statements of Operations [Abstract]
Sales	$ 99,615		$ 1,904		$ 125,876		$ 4,922		$ 170,263
Operating costs and expenses:
Cost of goods sold	(42,923)		(5,576)		(59,600)		(11,526)		(132,003)
Selling, general and administrative	(13,817)		(4,254)		(22,156)		(8,734)		(56,203)
Stock-based compensation	(412)		(15,133)		(3,311)		(15,133)		(32,441)
Depreciation and amortization	(283)		(61)		(366)		(156)		(895)
Accretion expense	(240)		(216)		(474)		(479)		(2,642)
Operating income (loss)	41,940		(23,336)		39,969		(31,106)		(53,921)
Other income (expense):
Other income (expense)	133		45		(35)		66		355
Interest income, net	70				210				275
Total other income (expense)	203		45		175		66		630
Income (loss) before income taxes	42,143		(23,291)		40,144		(31,040)		(53,291)
Income tax benefit	6,612				6,413				6,413
Net income (loss)	48,755		(23,291)		46,557		(31,040)		(46,878)
Net (income) loss attributable to noncontrolling interest	(968)				(968)				(968)
Net income (loss) attributable to Molycorp stockholders	47,787		(23,291)		45,589		(31,040)		(47,846)
Net income (loss)	48,755		(23,291)		46,557		(31,040)		(46,878)
Other comprehensive income:
Foreign currency translation adjustments	1,324				1,324				1,324
Comprehensive income (loss)	50,079		(23,291)		47,881		(31,040)		(45,554)
Comprehensive income (loss) attributable to:
Molycorp stockholders	48,980		(23,291)		46,782		(31,040)		(46,653)
Noncontrolling interest	1,099				1,099				1,099
Comprehensive income (loss)	$ 50,079		$ (23,291)		$ 47,881		$ (31,040)		$ (45,554)
Weighted average shares outstanding (Common shares) (1)
Basic	83,847,119	[1]	49,666,732	[1]	83,054,811	[1]	48,165,914	[1]	53,957,611	[1]
Diluted	84,413,499	[1]	49,666,732	[1]	83,339,566	[1]	48,165,914	[1]	53,957,611	[1]
Income (loss) per share of common stock (Note 4o):
Basic	$ 0.52		$ (0.47)		$ 0.50		$ (0.64)		$ (0.97)
Diluted	$ 0.52		$ (0.47)		$ 0.50		$ (0.64)		$ (0.97)

[1] Weighted average shares outstanding include the retroactive treatment of exchange ratios for conversion of Class A common stock and Class B common stock to common stock in conjunction with the initial public offering.