Consolidated debt to earnings before interest taxes depreciation ratio as per amended credit agreement.

No definition available.

Name:	trex_ConsolidatedDebtToEarningsBeforeInterestTaxesDepreciationAmortizationRatioAsPerCreditAgreement
Namespace Prefix:	trex_
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Balance Type:	na
Period Type:	duration

- Definition

Fixed charge coverage ratio as per credit agreement.

+ References

No definition available.

+ Details

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- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

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

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

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

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions 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

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Description of the conditions for borrowing under the credit facility including the nature of any restrictions.

+ 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 210.5-02.19(b),22(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityCovenantTerms
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LineOfCreditFacilityLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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

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

- Details

Name:	us-gaap_CreditFacilityAxis=trex_PriorCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
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Debt - Additional Information (Detail) (USD $)	12 Months Ended	3 Months Ended
Debt - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2014	Nov. 20, 2014	Jan. 06, 2012
Line of Credit Facility [Line Items]
Company indebtedness	$ 0us-gaap_DebtInstrumentCarryingAmount	0us-gaap_DebtInstrumentCarryingAmount
Credit facility covenant terms	(a) Fixed Charge Coverage Ratio. The Fixed Charge Coverage Ratio is not permitted to be less than 1.5 to 1.0, measured as of the end of each Fiscal Quarter, commencing with the Fiscal Quarter ended September 30, 2014. (b) Consolidated Debt to Consolidated EBITDA Ratio. The Consolidated Debt to Consolidated EBITDA Ratio is not permitted to exceed 3.00 to 1.0 measured as of the end of each Fiscal Quarter (and in the case of Consolidated EBITDA, for the four-quarter period ending on such date).
Second Amended Credit Agreement [Member]
Line of Credit Facility [Line Items]
Interest rate on the revolving credit facility	1.30%	1.30%
Termination date of the Credit Agreement	Nov. 20, 2019
Additional available borrowing capacity	100,000,000	100,000,000
Outstanding borrowings under the revolver loans	0	0
Second Amended Credit Agreement [Member] \| Revolver Loans Portion Effective January 1 through June 30 [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount			150,000,000
Second Amended Credit Agreement [Member] \| Revolver Loans Portion Effective July 1 through December 31 [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount			100,000,000
Second Amended Credit Agreement [Member] \| Letter of Credit Facility Sublimit [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount			15,000,000
Second Amended Credit Agreement [Member] \| Swing Advance Loan Sublimit [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount			5,000,000
Second Amended Credit Agreement [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Fixed charge coverage ratio as per credit agreement		1.5
Second Amended Credit Agreement [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Consolidated debt to earnings before interest taxes depreciation amortization ratio as per the credit agreement		3.00
Prior Credit Agreement [Member] \| Revolver Loans [Member]
Line of Credit Facility [Line Items]
Revolving loans in a collective maximum principal amount				$ 100,000,000