XML 85 R70.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Employee Benefit Plans - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of employee's contribution to the plan up to 6% of base salary matched by the Company | 100.00% |  |
Employer's contribution percentage | 6.00% |  |
Employer's contribution | $ 3,000,000 | $ 2,500,000 | $ 2,200,000
401(k) Profit Sharing Plan Two [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer's contribution percentage | 6.00% |  |
Employer contribution to the plan for every $1.00 contributed by an employee | $ 0.25 |  |
Employee's contribution to the plan up to 6% of base salary by the company | $ 1.00 |  |

X
- Definition Defined contribution plan employee additional contribution amount. + References No definition available. + Details
Name: | trex_DefinedContributionPlanEmployeeAdditionalContributionAmount
Namespace Prefix: | trex_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage employer matches of the employee's percentage contribution matched. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PlanNameAxis=trex_ProfitSharing401KPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |