Stockholders' Equity - Fair Value Assumptions for Options Granted (Details)	12 Months Ended
	Dec. 31, 2025 $ / shares
January 2, 2025
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	4.30%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.20%
Expected Stock Volatility	27.36%
Estimated Fair Value of Stock Option (in dollars per share)	$ 8.86
January 2, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	3.80%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.20%
Expected Stock Volatility	28.44%
Estimated Fair Value of Stock Option (in dollars per share)	$ 7.94
January 3, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	4.00%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.60%
Expected Stock Volatility	29.58%
Estimated Fair Value of Stock Option (in dollars per share)	$ 5.81
January 3, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	1.30%
Expected Life of Option in Years	5 years
Expected Dividend Yield	1.70%
Expected Stock Volatility	28.52%
Estimated Fair Value of Stock Option (in dollars per share)	$ 6.84
January 4, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	0.40%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.00%
Expected Stock Volatility	29.17%
Estimated Fair Value of Stock Option (in dollars per share)	$ 4.79
January 2, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	1.70%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.40%
Expected Stock Volatility	25.70%
Estimated Fair Value of Stock Option (in dollars per share)	$ 3.41
January 2, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	2.50%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.90%
Expected Stock Volatility	23.96%
Estimated Fair Value of Stock Option (in dollars per share)	$ 2.20
January 2, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	2.20%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.30%
Expected Stock Volatility	23.45%
Estimated Fair Value of Stock Option (in dollars per share)	$ 2.51
January 3, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free Interest Rate	1.90%
Expected Life of Option in Years	5 years
Expected Dividend Yield	2.60%
Expected Stock Volatility	24.49%
Estimated Fair Value of Stock Option (in dollars per share)	$ 2.10

FASTENAL CO 10-K