Agreement to invest during year.

No definition available.

Name:	rex_AgreementToInvestDuringYear
Namespace Prefix:	rex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Equity method initial investments.

+ References

No definition available.

+ Details

Name:	rex_EquityMethodInitialInvestments
Namespace Prefix:	rex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	rex_INVESTMENTSANDDEPOSITSDetailsLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Proportionate share of restricted net assets as of the reporting date.

+ References

No definition available.

+ Details

Name:	rex_ProportionateShareOfRestrictedNetAssets
Namespace Prefix:	rex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Quantity of ethanol shipped.

+ References

No definition available.

+ Details

Name:	rex_QuantityOfEthanolShipped
Namespace Prefix:	rex_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents disclosure of the amount of dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporation; these investments are accounted for under the equity method of accounting. This element excludes distributions that constitute a return of investment, which are classified as investing activities.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentDividendsOrDistributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the entity's ownership percentage in the investee multiplied by the investee's total equity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.12)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 7

+ Details

Name:	us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total assets that cannot be used for operating purposes because of contract or regulatory requirements that are in effect for a period that extends beyond one year.

+ References

+ Details

Name:	us-gaap_OtherRestrictedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of consolidated retained earnings that represent undistributed (not yet received) earnings from 50% or less owned persons accounted for by the equity method (equity method investees).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6462270&loc=d3e57205-112772

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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- Details

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INVESTMENTS AND DEPOSITS (Details) (USD $)	12 Months Ended
INVESTMENTS AND DEPOSITS (Details) (USD $)	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Income (Loss) from Equity Method Investments	$ 32,229,000	$ 17,175,000	$ 627,000
Equity Method Investments	80,389,000us-gaap_EquityMethodInvestments	71,189,000us-gaap_EquityMethodInvestments
Retained Earnings, Undistributed Earnings from Equity Method Investees	41,900,000	32,600,000
Big River [Member] \| Big River Resources United Energy LLC [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Equity Method Investment, Ownership Percentage	50.50%
Big River [Member] \| Burlington [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Quantity of ethanol shipped (in US Gallons)	108,000,000
Big River [Member] \| Illinois [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Quantity of ethanol shipped (in US Gallons)	119,000,000
Big River [Member] \| Dyersville [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Quantity of ethanol shipped (in US Gallons)	125,000,000
Big River [Member] \| Boyceville [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Quantity of ethanol shipped (in US Gallons)	58,000,000
Big River [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Agreement to Invest During Year	20,000,000
Equity Method Investment, Ownership Percentage	10.00%
Income (Loss) from Equity Method Investments	18,200,000	8,800,000	300,000
Proceeds from Equity Method Investment, Dividends or Distributions	18,000,000	1,200,000	2,200,000
Equity Method Investments	40,188,000	40,042,000
Equity Method Investment, Underlying Equity in Net Assets	40,700,000
Patriot [Member] \| Illinois [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Quantity of ethanol shipped (in US Gallons)	126,000,000
Patriot [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Equity Method Investment, Ownership Percentage	27.00%
Income (Loss) from Equity Method Investments	14,000,000	8,400,000	400,000
Proceeds from Equity Method Investment, Dividends or Distributions	4,900,000	4,600,000
Equity Method Investments	40,201,000	31,147,000
Equity Method Investment, Underlying Equity in Net Assets	38,900,000
Equity Method Initial Investments	17,900,000
Patriot And Big River [Member]
INVESTMENTS AND DEPOSITS (Details) [Line Items]
Other Restricted Assets	421,900,000
Proportionate Share of Restricted Net Assets	$ 57,700,000