Fair Value Measurements - Additional Information (Detail) - Facility	6 Months Ended	12 Months Ended
Jun. 30, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Number of storage facilities acquired	15	33

The number of businesses acquired by the entity during the period.

No definition available.

Name:	us-gaap_NumberOfBusinessesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration