Subsequent Events - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended				1 Months Ended		12 Months Ended					0 Months Ended		12 Months Ended		1 Months Ended		0 Months Ended		12 Months Ended
	Sep. 22, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 12, 2013	Feb. 28, 2013 USA Self Storage I, DST	Feb. 28, 2011 USA Self Storage I, DST Vendor	Dec. 31, 2013 USA Self Storage I, DST sqft Facility	Dec. 31, 2013 USA Self Storage I, DST San Francisco Loan	Dec. 31, 2013 KeyBank Revolver		Oct. 28, 2013 KeyBank Revolver	Mar. 21, 2014 Subsequent Event	Mar. 13, 2014 Subsequent Event Facility sqft	Dec. 31, 2013 Subsequent Event	Mar. 20, 2014 Subsequent Event	Feb. 25, 2014 Subsequent Event USA Self Storage I, DST Investors	Jan. 01, 2014 Subsequent Event USA Self Storage I, DST San Francisco Loan	Mar. 05, 2014 Subsequent Event Hampton, VA sqft Facility	Mar. 27, 2014 Subsequent Event Chandler, AZ Facility sqft	Dec. 31, 2013 Subsequent Event RETI I and RETI II [Member]	Dec. 31, 2013 Subsequent Event KeyBank Revolver Minimum	Dec. 31, 2013 Subsequent Event KeyBank Revolver Maximum
Subsequent Event [Line Items]
Percentage of voting interests acquired																	86.00%
Number of third-party sellers							40										45
Business acquisition purchase price							$ 37,550,000							$ 3,800,000			$ 20,000,000		$ 6,700,000	$ 4,900,000
Beneficial interest owned after transactions																	98.00%
Beneficial interest previously acquired																	12.00%
Business acquisition cash paid							10,200,000										10,200,000
Number of limited partnership units issued							70,000										245,000
Acquisition fees paid to the Advisor		1,700,000	2,200,000			377,000											200,000		200,000	100,000
Self storage facilities volume								1,120						900					500	480
Self storage facilities capacity								76,000						80,000					70,000	51,000
Lease term								10 years
Lease expiry date								Dec. 19, 2016
Aggregate principal balance		390,371,923																10,200,000
Fixed interest rate									5.84%	1.67%	[1]
Maturity date									Jan. 01, 2017	Oct. 25, 2016	[1]
Debt payment description							The Bank of America Loans required monthly interest-only payments during the first three years of their terms and now require monthly principal-and-interest payments based on a 30-year amortization period.	The Bank of America Loans required monthly interest-only payments during the first three years of their terms and now require monthly principal-and-interest payments based on a 30-year amortization period.	The San Francisco Loan required monthly interest-only payments during the first five years of its term and now requires monthly principal-and-interest payments based on a 30-year amortization period.
Debt amortization period							30 years		30 years
Maximum borrowings under revolving loan												75,000,000										75,000,000	100,000,000
Common stock per share outstanding per day declared					$ 0.001917808											$ 0.001917808
Dividend declared date		Mar. 20, 2014
Shares issued pursuant to distribution reinvestment plan	10,000,000												900,000
Issuance of shares pursuant to distribution reinvestment plan		$ 15,796,431	$ 12,311,983	$ 9,045,444									$ 9,000,000
Subordinated distributions description															In the case of each of the foregoing distributions, our Advisor's receipt of the distribution is subordinate to return of capital to our stockholders plus at least a 6% cumulative, non-compounded return, and our Advisor's share of the distribution is 5%, 10%, or 15%, depending on the return level to our stockholders.						The receipt of the distribution by the advisors to REIT I and REIT II is subordinate to return of capital to the original REIT I and REIT II stockholders plus at least a 7% cumulative, non-compounded return, and such advisors' share of the distribution is 15%.

[1] On October 28, 2013, through our Operating Partnership and certain property-owning special purpose entities wholly-owned by our Operating Partnership, we entered into the KeyBank Revolver, which matures on October 25, 2016. Such loan encumbers the Homeland Portfolio properties, the Knoxville Portfolio properties and five other previously unencumbered properties (Gulf Breeze II, El Paso I, Toms River II, North Charleston and Phoenix I). This loan is a LIBOR based variable rate loan, and such rate is based on 30-day LIBOR, which including the applicable spread equaled an initial interest rate of 1.67% as of October 28, 2013 and remained at such interest rate as of December 31, 2013. The interest rate swap with a notional amount of $45 million that was originally entered into in connection with the Second Restated KeyBank Loan remains outstanding; inclusive of the interest rate swap, the effective fixed interest rate as of December 31, 2013 was approximately 2.4%. For additional discussion, see "KeyBank Revolver" below.