STORAGE FACILITIES (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012 property	Dec. 31, 2011 property	Dec. 31, 2010 property
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	26	19	16
Acquisitions
STORAGE FACILITIES
Number of Facilities, acquisitions	37	27	12
Purchase / Sales Price	432,340,000	467,147,000	85,145,000
Acquisitions | Houston, Texas
STORAGE FACILITIES
Number of Facilities, acquisitions	1	1
Purchase / Sales Price	5,100,000	7,600,000
Acquisitions | Dunwoody, Georgia
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	6,900,000
Acquisitions | Mansfield Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	4,970,000
Acquisitions | Texas Asset at multiple locations in TX
STORAGE FACILITIES
Number of Facilities, acquisitions	4
Purchase / Sales Price	18,150,000
Acquisitions | Allen Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	5,130,000
Acquisitions | Norwalk Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	5,000,000
Acquisitions | Storage Deluxe assets
STORAGE FACILITIES
Number of Facilities, acquisitions	6	16
Purchase / Sales Price	201,910,000	357,310,000
Acquisitions | Eisenhower Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	19,750,000
Acquisitions | New Jersey Assets
STORAGE FACILITIES
Number of Facilities, acquisitions	2
Purchase / Sales Price	10,750,000
Acquisitions | Georgia/ Florida Assets
STORAGE FACILITIES
Number of Facilities, acquisitions	3
Purchase / Sales Price	13,370,000
Acquisitions | Peachtree Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	3,100,000
Acquisitions | HSREV Assets
STORAGE FACILITIES
Number of Facilities, acquisitions	9
Purchase / Sales Price	102,000,000
Acquisitions | Leetsdale Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	10,600,000
Acquisitions | Orlando/ West Palm Beach Assets
STORAGE FACILITIES
Number of Facilities, acquisitions	2
Purchase / Sales Price	13,010,000
Acquisitions | Exton/ Cherry Hill Assets
STORAGE FACILITIES
Number of Facilities, acquisitions	2
Purchase / Sales Price	7,800,000
Acquisitions | Carrollton Asset
STORAGE FACILITIES
Number of Facilities, acquisitions	1
Purchase / Sales Price	4,800,000
Acquisitions | Burke Lake Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		14,000,000
Acquisitions | West Dixie Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		13,500,000
Acquisitions | White Plains Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		23,000,000
Acquisitions | Phoenix Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		612,000
Acquisitions | Duluth Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		2,500,000
Acquisitions | Atlanta Assets
STORAGE FACILITIES
Number of Facilities, acquisitions		2
Purchase / Sales Price		6,975,000
Acquisitions | District Heights Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		10,400,000
Acquisitions | Leesburg Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		13,000,000
Acquisitions | Washington, DC Asset
STORAGE FACILITIES
Number of Facilities, acquisitions		1
Purchase / Sales Price		18,250,000
Acquisitions | Frisco Asset
STORAGE FACILITIES
Number of Facilities, acquisitions			1
Purchase / Sales Price			5,800,000
Acquisitions | New York City Assets
STORAGE FACILITIES
Number of Facilities, acquisitions			2
Purchase / Sales Price			26,700,000
Acquisitions | Northeast Assets
STORAGE FACILITIES
Number of Facilities, acquisitions			5
Purchase / Sales Price			18,560,000
Acquisitions | Manassas Asset
STORAGE FACILITIES
Number of Facilities, acquisitions			1
Purchase / Sales Price			6,050,000
Acquisitions | Apopka Asset
STORAGE FACILITIES
Number of Facilities, acquisitions			1
Purchase / Sales Price			4,235,000
Acquisitions | Wyckoff Asset
STORAGE FACILITIES
Number of Facilities, acquisitions			1
Purchase / Sales Price			13,600,000
Acquisitions | McLearen Asset
STORAGE FACILITIES
Number of Facilities, acquisitions			1
Purchase / Sales Price			10,200,000
Dispositions
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	26	19	16
Purchase / Sales Price	59,962,000	45,200,000	38,100,000
Dispositions | Michigan Assets
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	3
Purchase / Sales Price	6,362,000
Dispositions | Gulf Coast Assets at multiple locations in LA, AL and MS
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	5
Purchase / Sales Price	16,800,000
Dispositions | New Mexico Assets
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	6
Purchase / Sales Price	7,500,000
Seller financing provided to buyer	5,300,000
Dispositions | San Bernardino Asset
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	1
Purchase / Sales Price	5,000,000
Dispositions | Florida/ Tennessee Assets
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	3
Purchase / Sales Price	6,550,000
Dispositions | Ohio Assets
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)	8
Purchase / Sales Price	17,750,000
Dispositions | Flagship Assets
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)		18
Purchase / Sales Price		43,500,000
Dispositions | Portage Asset
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)		1
Purchase / Sales Price		1,700,000
Dispositions | Sun City Asset
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)			1
Purchase / Sales Price			3,100,000
Dispositions | Inland Empire Fayetteville Assets
STORAGE FACILITIES
Number of Facilities, dispositions (in properties)			15
Purchase / Sales Price			35,000,000