Derivative, Cap Coverage Rate

No definition available.

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Period Type:	instant

- Definition

Fixed charge coverage ratio.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of credit facility additional increase In maximum borrowing capacity.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of credit facility basis spread on variable rate.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility limitation amount.

+ References

No definition available.

+ Details

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
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- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

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- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

+ References

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Period Type:	duration

- Definition

Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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- Definition

Face (par) amount of debt instrument at time of issuance.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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Period Type:	instant

- Definition

Increase for accrued, but unpaid interest on the debt instrument for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 1
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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer.

+ References

No definition available.

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Line-of-Credit Arrangement
-URI http://asc.fasb.org/extlink&oid=6517033

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20
-Article 5

+ Details

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

- Definition

The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

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Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Details

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- Details

Name:	us-gaap_LineOfCreditFacilityAxis=regi_WellsFargoRevolverMember
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- Details

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Debt - (Details Textual)		1 Months Ended	12 Months Ended
Debt - (Details Textual)	Jul. 08, 2014 USD ($)	Jun. 30, 2014 USD ($) $ / shares $ / Warrant	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Short-term Debt [Line Items]
Cash received on convertible debt			$ 0	$ 143,750,000	$ 0
Available borrowing capacity			46,216,000
Revolving line of credit			23,149,000	16,679,000
Maximum remaining available to be borrowed under revolving line of credit			$ 23,067,000	$ 20,719,000
REG Mason City term loan, fixed interest rate of 5%, due in July 2019
Short-term Debt [Line Items]
Interest rate			5.00%	5.00%
Wells Fargo Revolver
Short-term Debt [Line Items]
Additional increase in maximum borrowing capacity			$ 60,000,000
Fixed Charge Coverage Ratio			100.00%
Excess Availability			$ 6,000,000
Line Of Credit Facility Limitation Amount			$ 25,000,000
Wells Fargo Revolver \| Maximum
Short-term Debt [Line Items]
LIBOR Rate Margin			4.25%
Wells Fargo Revolver \| Minimum
Short-term Debt [Line Items]
LIBOR Rate Margin			2.50%
REG Ames term loans, secured, fixed interest rates of 3.5% and 4.25%, due in January 2018 and December 2019, respectively \| Maximum
Short-term Debt [Line Items]
Interest rate			4.25%	4.25%
REG Ames term loans, secured, fixed interest rates of 3.5% and 4.25%, due in January 2018 and December 2019, respectively \| Minimum
Short-term Debt [Line Items]
Interest rate			3.50%	3.50%
REG Grays Harbor \| Minimum
Short-term Debt [Line Items]
Interest rate			3.50%	3.50%
REG Danville, LLC
Short-term Debt [Line Items]
Interest to be accrued			LIBOR plus 5% per annum	LIBOR plus 5% per annum
Reg Newton
Short-term Debt [Line Items]
Interest to be accrued			LIBOR plus 4% per annum	LIBOR plus 4% per annum
REG Grays Harbor
Short-term Debt [Line Items]
Interest to be accrued			Minimum 3.% or Prime Rate plus 0.25%	Minimum 3.% or Prime Rate plus 0.25%
Gulf Opportunity Zone Bonds
Short-term Debt [Line Items]
Value of notes issued	$ 100,000,000
Letter of credit	101,315,000
Interest	1,315,000
Amount owed	$ 101,315,000
2.75% Convertible debt, $143,750 face amount, due in June 2019
Short-term Debt [Line Items]
Value of notes issued		$ 143,750,000	$ 143,750,000	$ 143,750,000
Conversion rate		75.3963
Initial conversion price (in dollars per share) \| $ / shares		$ 13.26
Effective interest rate		3.80%
Cash received on convertible debt		$ 143,750,000
Percentage of shares covered by capped call		92.50%
Cap price \| $ / Warrant		16.02
Value of purchased capped calls		$ 11,904,000
Interest rate			2.75%	2.75%
Debt Instrument, Redemption, Period One \| 2.75% Convertible debt, $143,750 face amount, due in June 2019
Short-term Debt [Line Items]
Threshold Percentage of Stock Price Trigger		130.00%
Debt Instrument, Redemption, Period Two \| 2.75% Convertible debt, $143,750 face amount, due in June 2019
Short-term Debt [Line Items]
Threshold Percentage of Stock Price Trigger		98.00%
Long-term Debt \| 2.75% Convertible debt, $143,750 face amount, due in June 2019
Short-term Debt [Line Items]
Cash received on convertible debt		$ 118,719,000
Stockholders' Equity, Total \| 2.75% Convertible debt, $143,750 face amount, due in June 2019
Short-term Debt [Line Items]
Cash received on convertible debt		25,031,000
Deferred Financing and Equity Costs \| 2.75% Convertible debt, $143,750 face amount, due in June 2019
Short-term Debt [Line Items]
Cash received on convertible debt		$ 4,563,000
LIBOR \| REG Danville, LLC
Short-term Debt [Line Items]
Variable interest rate			5.00%	5.00%
LIBOR \| Reg Newton
Short-term Debt [Line Items]
Variable interest rate			4.00%	4.00%
Prime Rate \| REG Grays Harbor
Short-term Debt [Line Items]
Variable interest rate			0.25%	0.25%