Benefit plans (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2020	Feb. 01, 2019	Feb. 02, 2018
Benefit plans
Matching contribution expense related to the Company's 401(k) plan	$ 25.0	$ 20.2	$ 17.5
Compensation expense for the Dollar General Corporation CDP/SERP Plan	$ 0.8	$ 0.7	$ 0.7