EBP, Employee Contribution Vesting Percentage

No definition available.

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- Definition

EBP, Employer Contribution, Minimum Age

+ References

No definition available.

+ Details

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- Definition

EBP, Investment Options, Maximum Contribution Investment In Company Stock, Percentage

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

EBP, Participant Contribution, Maximum Annual Compensation to Total Compensation, Percentage

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Participant Contribution, Minimum Annual Compensation to Total Compensation, Percentage

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Payment Of Benefits, Maximum Number Of Partial Distributions In Plan Year

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

EBP, Payment Of Benefits, Minimum Number Of Partial Distributions

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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Period Type:	duration

- Definition

EBP, Requisite Service Period

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

EBP, Roth Tax Treatment, Catch-Up Contribution Age

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

+ Details

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

- Definition

Amount of plan asset, in forfeited nonvested account, no longer allocated to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

+ Details

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Namespace Prefix:	us-gaap-ebp_
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Balance Type:	debit
Period Type:	instant

- Definition

Amount of decrease in forfeited nonvested account of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) from administrative expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(5)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

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

- Definition

Percentage of eligible compensation contributed for participant automatically enrolled in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Plan Description (Details) - Fastenal Company & Subsidiaries 401(k) and Employee Stock Ownership Plan		12 Months Ended
	Jan. 01, 2026 year	Dec. 31, 2025 USD ($) year distributionPayment	Dec. 31, 2024 USD ($)
Description of Plan [Line Items]
Minimum requisite service period		60 days
Minimum age to contribute		18
Higher catch-up contribution age		60
Employer contribution vesting percentage		100.00%
Automatic deferral rate		5.00%
Minimum annual compensation to total compensation, percentage		1.00%
Maximum annual compensation deferral percentage		100.00%
Maximum percentage of contribution investment in company stock		25.00%
Minimum number of partial distributions \| distributionPayment		2
Maximum number of partial distributions In plan year \| distributionPayment		4
Forfeited nonvested account \| $		$ 149,815	$ 43,859
Forfeited nonvested account, decrease from administrative expense \| $		$ 75,629
Discretionary Profit Sharing Contribution
Description of Plan [Line Items]
Employer contribution vesting percentage		100.00%
Minimum \| Subsequent Events
Description of Plan [Line Items]
Higher catch-up contribution age	60
Maximum
Description of Plan [Line Items]
Higher catch-up contribution age		63
Maximum \| Subsequent Events
Description of Plan [Line Items]
Higher catch-up contribution age	63