PRO FORMA FINANCIAL INFORMATION (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Self-storage facilities property	Dec. 31, 2013 Self-storage facilities property
Self-storage facilities
Number of self-storage facilities acquired (in properties)					19	20
Aggregate purchase or sales price					$ 230,700	$ 189,800
Consolidated results of operations on a pro forma basis
Pro forma revenues			182,946	170,013
Pro forma net income attributable to the Company's common shareholders			$ 20,805	$ (3,167)
Earnings (loss) per share from continuing operations attributable to common shareholders
Basic - as reported (in dollars per share)	$ 0.04	$ 0.00	$ 0.06	$ (0.03)
Diluted - as reported (in dollars per share)	$ 0.04	$ 0.00	$ 0.06	$ (0.03)
Basic - as pro forma (in dollars per share)			$ 0.15	$ (0.02)
Diluted - as pro forma (in dollars per share)			$ 0.14	$ (0.02)