Condensed Consolidating Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 227,790	$ 418,855	$ 316,430	$ 6,929
Trade accounts receivable, net (Note 2)	52,430	70,679
Inventory	287,376	111,943
Deferred charges	9,412	7,318
Deferred tax assets	9,789	0
Income tax receivable	25,087	10,514
Prepaid expenses and other current assets	21,794	19,735
Total current assets	633,678	639,044
Non-current assets:
Deposits	26,769	23,286
Property, plant and equipment, net	1,544,304	561,628
Inventory	26,096	4,362
Intangible assets, net	450,938	3,072
Investments	64,036	20,000
Deferred tax assets	0
Goodwill	239,742	3,432	0
Investments in consolidated subsidiaries	0	0
Intercompany accounts receivable	0	0
Other non-current assets	6,972	301
Total non-current assets	2,358,857	616,081
Total assets	2,992,535	1,255,125
Current liabilities:
Trade accounts payable	241,994	161,587
Accrued expenses	59,013	12,898
Income tax payable	15,267	0
Deferred tax liabilities	0	1,356
Debt and capital lease obligations	39,604	1,516
Short-term borrowings-related party		870
Other current liabilities	3,539	1,266
Current portion of asset retirement obligation		396
Total current liabilities	359,417	178,623
Non-current liabilities:
Asset retirement obligation	18,586	15,145
Deferred tax liabilities	160,675	18,899
Debt and capital lease obligations	1,188,832	196,545
Derivative liability	7,816	0
Pension liabilities	3,292	0
Intercompany accounts payable	0	0
Other non-current liabilities	2,659	683
Total non-current liabilities	1,381,860	231,272
Total liabilities	1,741,277	409,895
Stockholders’ equity:
Common stock	139	84
Preferred stock	2	2
Additional paid-in capital	1,691,429	838,547
Accumulated other comprehensive loss	(9,433)	(8,481)
(Deficit) retained earnings	(466,091)	15,078
Total Molycorp stockholders’ equity	1,216,046	845,230
Noncontrolling interests	35,212	0
Total stockholders’ equity	1,251,258	845,230	446,513	74,615
Total liabilities and stockholders’ equity	2,992,535	1,255,125
Parent
Current assets:
Cash and cash equivalents	16,560	407,446	316,430	0
Trade accounts receivable, net (Note 2)	0	0
Inventory	0	0
Deferred charges	0	0
Deferred tax assets	0
Income tax receivable	0	0
Prepaid expenses and other current assets	0	0
Total current assets	16,560	407,446
Non-current assets:
Deposits	1,752	1,751
Property, plant and equipment, net	0	0
Inventory	0	0
Intangible assets, net	0	0
Investments	0	0
Deferred tax assets	6,030
Goodwill	0	0
Investments in consolidated subsidiaries	883,319	150,510
Intercompany accounts receivable	1,539,877	476,711
Other non-current assets	0	0
Total non-current assets	2,430,978	628,972
Total assets	2,447,538	1,036,418
Current liabilities:
Trade accounts payable	0	0
Accrued expenses	14,872	311
Income tax payable	0
Deferred tax liabilities	0	0
Debt and capital lease obligations	0	0
Short-term borrowings-related party		0
Other current liabilities	0
Current portion of asset retirement obligation		0
Total current liabilities	14,872	311
Non-current liabilities:
Asset retirement obligation	0	0
Deferred tax liabilities	0	0
Debt and capital lease obligations	1,166,777	190,877
Derivative liability	0
Pension liabilities	0
Intercompany accounts payable	49,843	0
Other non-current liabilities	0	0
Total non-current liabilities	1,216,620	190,877
Total liabilities	1,231,492	191,188
Stockholders’ equity:
Common stock	139	84
Preferred stock	2	2
Additional paid-in capital	1,691,429	838,547
Accumulated other comprehensive loss	(9,433)	(8,481)
(Deficit) retained earnings	(466,091)	15,078
Total Molycorp stockholders’ equity	1,216,046
Noncontrolling interests	0
Total stockholders’ equity	1,216,046	845,230
Total liabilities and stockholders’ equity	2,447,538	1,036,418
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	18,020	10,758	0	6,929
Trade accounts receivable, net (Note 2)	7,738	58,619
Inventory	49,416	52,246
Deferred charges	2,203	7,318
Deferred tax assets	0
Income tax receivable	25,087	10,514
Prepaid expenses and other current assets	9,085	17,845
Total current assets	111,549	157,300
Non-current assets:
Deposits	24,862	21,362
Property, plant and equipment, net	1,377,147	500,612
Inventory	26,096	4,362
Intangible assets, net	508	573
Investments	45,241	20,000
Deferred tax assets	0
Goodwill	0	1,977
Investments in consolidated subsidiaries	97,960	118,879
Intercompany accounts receivable	207,035	25,870
Other non-current assets	885	301
Total non-current assets	1,779,734	693,936
Total assets	1,891,283	851,236
Current liabilities:
Trade accounts payable	191,769	139,408
Accrued expenses	10,087	11,072
Income tax payable	0
Deferred tax liabilities	1,942	1,356
Debt and capital lease obligations	352	0
Short-term borrowings-related party		870
Other current liabilities	3,539
Current portion of asset retirement obligation		396
Total current liabilities	207,689	153,102
Non-current liabilities:
Asset retirement obligation	18,586	15,145
Deferred tax liabilities	23,130	18,899
Debt and capital lease obligations	15,163	0
Derivative liability	0
Pension liabilities	0
Intercompany accounts payable	1,577,363	489,180
Other non-current liabilities	1,102	683
Total non-current liabilities	1,635,344	523,907
Total liabilities	1,843,033	677,009
Stockholders’ equity:
Common stock	0	0
Preferred stock	0	0
Additional paid-in capital	149,857	149,857
Accumulated other comprehensive loss	0	0
(Deficit) retained earnings	(101,607)	24,370
Total Molycorp stockholders’ equity	48,250
Noncontrolling interests	0
Total stockholders’ equity	48,250	174,227
Total liabilities and stockholders’ equity	1,891,283	851,236
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	193,210	651	0
Trade accounts receivable, net (Note 2)	44,692	12,060
Inventory	237,960	59,697
Deferred charges	7,209	0
Deferred tax assets	11,731
Income tax receivable	0	0
Prepaid expenses and other current assets	12,709	1,890
Total current assets	507,511	74,298
Non-current assets:
Deposits	155	173
Property, plant and equipment, net	167,157	61,016
Inventory	0	0
Intangible assets, net	450,430	2,499
Investments	18,795	0
Deferred tax assets	0
Goodwill	239,742	1,455
Investments in consolidated subsidiaries	0	0
Intercompany accounts receivable	794	0
Other non-current assets	6,087	0
Total non-current assets	883,160	65,143
Total assets	1,390,671	139,441
Current liabilities:
Trade accounts payable	50,225	22,179
Accrued expenses	34,054	1,515
Income tax payable	15,267
Deferred tax liabilities	0	0
Debt and capital lease obligations	39,252	1,516
Short-term borrowings-related party		0
Other current liabilities	0
Current portion of asset retirement obligation		0
Total current liabilities	138,798	25,210
Non-current liabilities:
Asset retirement obligation	0	0
Deferred tax liabilities	143,575	0
Debt and capital lease obligations	6,892	5,668
Derivative liability	7,816
Pension liabilities	3,292
Intercompany accounts payable	120,500	13,401
Other non-current liabilities	1,557	0
Total non-current liabilities	283,632	19,069
Total liabilities	422,430	44,279
Stockholders’ equity:
Common stock	0	0
Preferred stock	0	0
Additional paid-in capital	1,283,863	91,158
Accumulated other comprehensive loss	(9,433)	(8,481)
(Deficit) retained earnings	(341,401)	12,485
Total Molycorp stockholders’ equity	933,029
Noncontrolling interests	35,212
Total stockholders’ equity	968,241	95,162
Total liabilities and stockholders’ equity	1,390,671	139,441
Eliminations
Current assets:
Cash and cash equivalents	0	0	0	0
Trade accounts receivable, net (Note 2)	0	0
Inventory	0	0
Deferred charges	0	0
Deferred tax assets	(1,942)
Income tax receivable	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(1,942)	0
Non-current assets:
Deposits	0	0
Property, plant and equipment, net	0	0
Inventory	0	0
Intangible assets, net	0	0
Investments		0
Deferred tax assets	(6,030)
Goodwill	0	0
Investments in consolidated subsidiaries	(981,279)	(269,389)
Intercompany accounts receivable	(1,747,706)	(502,581)
Other non-current assets	0	0
Total non-current assets	(2,735,015)	(771,970)
Total assets	(2,736,957)	(771,970)
Current liabilities:
Trade accounts payable	0	0
Accrued expenses	0	0
Income tax payable	0
Deferred tax liabilities	(1,942)	0
Debt and capital lease obligations	0	0
Short-term borrowings-related party		0
Other current liabilities	0
Current portion of asset retirement obligation		0
Total current liabilities	(1,942)	0
Non-current liabilities:
Asset retirement obligation	0	0
Deferred tax liabilities	(6,030)	0
Debt and capital lease obligations	0	0
Derivative liability	0
Pension liabilities	0
Intercompany accounts payable	(1,747,706)	(502,581)
Other non-current liabilities	0	0
Total non-current liabilities	(1,753,736)	(502,581)
Total liabilities	(1,755,678)	(502,581)
Stockholders’ equity:
Common stock	0	0
Preferred stock	0	0
Additional paid-in capital	(1,433,720)	(241,015)
Accumulated other comprehensive loss	9,433	8,481
(Deficit) retained earnings	443,008	(36,855)
Total Molycorp stockholders’ equity	(981,279)
Noncontrolling interests	0
Total stockholders’ equity	(981,279)	(269,389)
Total liabilities and stockholders’ equity	$ (2,736,957)	$ (771,970)