Commitments and Contingencies - Additional Information (Detail) - Jun. 30, 2015 $ in Millions	USD ($) Facility
Commitments and Contingencies Disclosure [Abstract]
Payment for self-storage facilities under contract \| $	$ 85.4
Number of self-storage facilities under contract to be purchased	13

Contracted acquisition price of self storage facility.

No definition available.

Name:	sss_ContractedAcquisitionPriceOfSelfStorageFacility
Namespace Prefix:	sss_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant