The cash outflow for acquisition of or capital improvements of property, plant and equipment, used to produce goods or deliver services, and not otherwise defined in the taxonomy.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3213-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 17

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Name:	us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified		9 Months Ended	12 Months Ended		9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended				9 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended
	Sep. 30, 2011 MT	Sep. 30, 2011 Bloom Lake [Member]	Dec. 31, 2012 Bloom Lake [Member]	Dec. 31, 2011 Bloom Lake [Member]	Sep. 30, 2011 Lower War Eagle [Member]	Dec. 31, 2011 Lower War Eagle [Member]	Sep. 30, 2011 Koolyanobbing [Member]	Dec. 31, 2012 Koolyanobbing [Member]	Dec. 31, 2011 Koolyanobbing [Member]	Dec. 31, 2010 Koolyanobbing [Member] MT	Sep. 30, 2011 Empire [Member] T	Sep. 30, 2011 Empire and Tilden [Member]	Dec. 31, 2012 Empire and Tilden [Member]	Dec. 31, 2011 Empire and Tilden [Member]	Sep. 30, 2011 Tilden [Member] T	Sep. 30, 2011 Oak Grove [Member]	Dec. 31, 2011 Oak Grove II [Member]
Capital investment committed		$ 206.0					$ 246.0					$ 178.0				$ 31.0
Gross post-project production capacity, tons	8,000,000									11,000,000	3,000,000				2,000,000
Capital investment paid		65.0			31.0		133.0					123.0				26.0
Capital investment, future payments		615.0	68.0	73.0	49.0	10.0	272.0	46.0	67.0			264.0	24.0	31.0		55.0	5.0
Capital Investment, 2012 scheduled payments					$ 8