Property Acquisitions and Dispositions - (Details)					1 Months Ended	12 Months Ended
	Jul. 26, 2016 USD ($)	Apr. 20, 2016 USD ($) store	Apr. 01, 2016 USD ($) shares	Oct. 01, 2015 USD ($) store $ / shares	Dec. 31, 2014 USD ($) store	Dec. 31, 2016 USD ($) store property	Dec. 31, 2015 USD ($) property	Dec. 31, 2014 USD ($)	Dec. 31, 2012 store	Feb. 01, 2017 USD ($)	Dec. 31, 2011 USD ($)
Property Acquisitions [Line Items]
Number of operating stores acquired | store						66
Number of stores excluded from pro forma financial information | store						33
Number of stores | property						99	171
Payment of earnout from prior acquisition						$ 4,600,000	$ 0	$ 0
Amount due to sellers resulting from higher rental income of properties						5,184,000	5,510,000
Strategic 1031 LLC [Member] | Real Estate Loan [Member]
Property Acquisitions [Line Items]
Notes receivable				$ 84,331,000		52,201,000
Notes receivable, interest rate				7.00%
SmartStop Self Storage, Inc (SmartStop) [Member]
Property Acquisitions [Line Items]
Purchase price per share | $ / shares				$ 13.75
Total purchase price				$ 1,391,272,000
Expense related to defeasance costs and prepayment penalties				38,360,000
Professional fees/closing costs				8,053,000
Severance-related costs				6,338,000
Other payroll-related costs				1,327,000
Total expense paid				54,078,000
Other acquisition related costs				9,043,000
Total expense not paid				$ 63,121,000
Canada [Member]
Property Acquisitions [Line Items]
Number of stores excluded from the Company's acquisition | store				5
New Jersey and Virginia, 5 Stores Acquired in 2014 [Member]
Property Acquisitions [Line Items]
Increase in payments due to sellers						$ 4,284,000
Number of operating stores acquired | store					5
New York and New Jersey, 10 Stores Acquired in 2012 [Member]
Property Acquisitions [Line Items]
Number of operating stores acquired | store									10
Term to make additional cash payment to sellers if the stores acquired exceeded a specified amount of net rental income									2 years
Payment of earnout from prior acquisition								7,785,000
Florida, Stores Acquired in 2011 [Member]
Property Acquisitions [Line Items]
Amount due to sellers resulting from higher rental income of properties					$ 2,500,000			$ 2,500,000			$ 133,000
Gain (loss) on earnout consideration							$ 400,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Disposal of Indiana Stores, July 26, 2016 [Member]
Property Acquisitions [Line Items]
Proceeds from sale of real estate held-for-investment	$ 4,447,000
Gain (loss) on disposition of assets	$ 0
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Disposal of Ohio and Indiana Stores, April 20, 2016 [Member]
Property Acquisitions [Line Items]
Proceeds from sale of real estate held-for-investment		$ 17,555,000
Number of stores sold | store		7
Gain (loss) on disposition of assets		$ 11,265,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Disposal of Texas Store, April 1, 2016 [Member]
Property Acquisitions [Line Items]
Gain (loss) on disposition of assets			$ 93,000
Partner capital units | shares			85,452
Consideration			$ 7,689,000
Subsequent Event [Member]
Property Acquisitions [Line Items]
Notes receivable, interest rate										9.00%
Subsequent Event [Member] | Strategic 1031 LLC [Member] | Real Estate Loan [Member]
Property Acquisitions [Line Items]
Notes receivable										$ 20,608,000