Commitments and contingencies (Details) - lawsuit	3 Months Ended
	Nov. 30, 2017	Aug. 31, 2016
Loss Contingencies [Line Items]
Duration for plaintiffs to file amended complaint	10 days
Rite Aid Transactions
Loss Contingencies [Line Items]
Number of lawsuits filed		2
State of Pennsylvania in the Court of Common Pleas of Cumberland County
Loss Contingencies [Line Items]
Number of lawsuits filed		1
Middle District of Pennsylvania
Loss Contingencies [Line Items]
Number of lawsuits filed		1
Delaware
Loss Contingencies [Line Items]
Lawsuits filed and dismissed	8