Commitments and contingencies (Details) - lawsuit	3 Months Ended	9 Months Ended
	Nov. 30, 2017	May 31, 2018	Aug. 31, 2017
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
United States District Court for the Middle District of Pennsylvania
Loss Contingencies [Line Items]
Number of lawsuits filed			1
Court of Chancery of the State of Delaware
Loss Contingencies [Line Items]
Lawsuits filed and dismissed		8