Leases - Narrative (Details) $ in Millions	Oct. 31, 2020 USD ($)
Leases [Abstract]
Leases signed but not yet commenced	$ 243.7

Lessee, Operating Lease, Lease Not yet Commenced, Amount

No definition available.

Name:	dltr_LesseeOperatingLeaseLeaseNotyetCommencedAmount
Namespace Prefix:	dltr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant