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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-3

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Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Subsequent Events (Details) - Fastenal Company & Subsidiaries 401(k) and Employee Stock Ownership Plan	Jun. 04, 2026 change	Dec. 31, 2025 distributionPayment
Subsequent Events [Line Items]
Maximum number of distributions per year \| distributionPayment		4
Subsequent Events
Subsequent Events [Line Items]
Number of changes after period end \| change	2