Retirement Savings Plan	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Retirement Savings Plan	Note 6. Retirement Savings PlanThe Fastenal Company and Subsidiaries 401(k) and Employee Stock Ownership Plan covers all of our employees in the United States. Our employees in Canada may participate in a Registered Retirement Savings Plan. The general purpose of both of these plans is to provide additional financial security during retirement by providing employees with an incentive to make regular savings contributions. In addition to the participation of our employees, we make annual profit sharing contributions based on an established formula. The expense recorded under this profit sharing formula was approximately $22.1, $17.4, and $16.2 for 2022, 2021, and 2020, respectively.