Subsequent event (Details) (Subsequent event, Family Dollar, Common stock, Forecast, USD $)	Aug. 18, 2014
Subsequent event \| Family Dollar \| Common stock \| Forecast
Subsequent event
Share price of stock acquired (in dollars per share)	$ 78.50

Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

No definition available.

Name:	us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant