NONCONTROLLING INTEREST REPRESENTED BY PREFERRED OPERATING PARTNERSHIP UNITS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended				1 Months Ended	0 Months Ended		1 Months Ended		9 Months Ended	0 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Series B Units	Jun. 30, 2007 Holders of A units Series A Units	Sep. 26, 2013 Operating Partnership property	Aug. 29, 2013 Operating Partnership property	Jun. 30, 2007 Operating Partnership property	Jun. 30, 2007 Operating Partnership Series A Units	Sep. 30, 2013 Operating Partnership Series A Units	Sep. 26, 2013 Operating Partnership Series B Units	Sep. 30, 2013 Operating Partnership Series B Units	Jun. 25, 2007 Operating Partnership Holders of A units
Noncontrolling interest represented by preferred operating partnership units
Number of self-storage facilities (properties) acquired						1	19	10
Preferred OP units issued as part of the acquisition (in shares)									989,980		1,342,727
Loan to holders of preferred OP units	$ 100,000		$ 100,000										$ 100,000
Note receivable interest rate (as a percent)								4.85%
Maximum number of preferred OP units converted prior to the maturity date of the loan (in shares)					114,500
Fixed priority return on preferred OP units, amount										115,000
Fixed priority return on preferred OP units, stated return rate (as a percent)										5.00%
Fixed priority return on preferred OP units, liquidation value										115,000
Number of self storage properties							20
Cash portion of payment for acquisition						100,876
Debt Assumed	7,122	147,592				98,960
Preferred OP units issued as part of the acquisition											33,568
Common OP units issued as part of the acquisition (in shares)						1,448,108
Common OP units issued as part of the acquisition						62,341
Fixed value (in dollars per share)				$ 25
Value of Series B units				$ 33,568								$ 33,568
Annual rate of return (as a percent)												6.00%