Secured Debt - Additional Information (Detail) (USD $)			0 Months Ended	12 Months Ended		0 Months Ended			0 Months Ended			12 Months Ended							0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Oct. 28, 2013 KeyBank Revolver	Dec. 31, 2013 KeyBank Revolver Property		Oct. 28, 2013 KeyBank Revolver Knoxville Portfolio	Dec. 31, 2013 KeyBank Revolver Maximum	Dec. 31, 2013 KeyBank Revolver Minimum	Oct. 28, 2013 Second Restated Key Bank Loan Property	Jan. 12, 2012 Second Restated Key Bank Loan	Dec. 27, 2011 Second Restated Key Bank Loan	Dec. 31, 2013 Second Restated Key Bank Loan Option		Apr. 05, 2013 Second Restated Key Bank Loan	Oct. 10, 2012 Second Restated Key Bank Loan	Dec. 27, 2011 Second Restated Key Bank Loan Atlanta Georgia Property	Dec. 27, 2011 Second Restated Key Bank Loan Jacksonville, Florida Property	Dec. 27, 2011 Restated Key Bank Credit Facility	Mar. 05, 2013 SF Bay Area - Morgan Hill	Dec. 31, 2013 SF Bay Area - Morgan Hill		Dec. 31, 2012 KeyBank Bridge Loan	Dec. 27, 2011 KeyBank Bridge Loan
Debt Instrument [Line Items]
Net book values of secured properties	$ 647,000,000	$ 587,000,000
Maximum borrowings under revolving loan			75,000,000								82,000,000							30,000,000
Revolving credit facility syndicated to another participating lender			25,000,000
Draw from revolving loan			71,000,000			26,000,000				5,400,000	56,600,000
Repayment of loan									45,000,000
Properties acquired									12							10	2
Revolving loan initial term				3 years
Line of credit facility maturity date				Oct. 25, 2016								Dec. 24, 2014
Interest rate swap amount									45,000,000			45,000,000
Initial interest rate of interest rate swap				1.67%
Current interest rate of interest rate of swap				2.40%								5.41%
Credit agreement description				The KeyBank Revolver has an initial term of three years, maturing on October 25, 2016, with two one-year extension options subject to certain conditions outlined further in the credit agreement for the KeyBank Revolver (the "Credit Agreement")								Subject to two, one-year extension options (subject to the fulfillment of certain conditions), and required monthly interest-only payments.
Increase in aggregate commitment amount							200,000,000	10,000,000
Reduction in aggregate commitments								10,000,000
Amount syndicated								25,000,000
Self storage properties				5
Other recourse debt				25,000,000								25,000,000
Other non-recourse debt				75,000,000								75,000,000
Percent of collateral properties used for aggregate borrowing capacity				60.00%
Debt Service Coverage Ratio				1.35
Total Leverage Ratio				60.00%
Minimum Tangible Net Worth				250,000,000
Minimum Interest Service Coverage Ratio				1.85
Minimum Fixed Charge Ratio				1.6
Ratio of varying rate Indebtedness				30.00%
Percentage of required Loan to Value Ratio				60.00%
Worth of portfolio											80,000,000
Amount outstanding under loan										82,000,000				45,000,000	55,000,000			20,000,000
Amount of monthly payments												1,666,667
Line of credit facility, potential term of extension options												1 year
Line of credit facility, number of extension options												2
Principal amount																			3,000,000				28,000,000
Commitments amount previously committed under KeyBank Working Capital Line																							$ 10,000,000
Debt instrument variable interest rate																						6.70%
Debt instrument variable interest rate description																						Under the terms of the KeyBank Bridge Loan, our Operating Partnership had the option of selecting one of three variable interest rates, which had applicable spreads. Our Operating Partnership elected to have a 30-day LIBOR rate apply, which, including the applicable spread, equaled an interest rate of approximately 6.7% for the period outstanding during 2012.
Term of loan maturity period																			30 years
Fixed rate of interest																			4.08%
Maturity date				Oct. 25, 2016	[1]							Dec. 24, 2014	[2]						Mar. 06, 2023	Apr. 01, 2013	[3]
Weighted average interest rate of fixed rate debt	5.40%

[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.

[2] Through October 28, 2013, this loan was collateralized by the Homeland Portfolio (Kennesaw, Sharpsburg, Duluth I, Duluth II, Duluth III, Marietta III, Austell, Sandy Springs, Smyrna, Lawrenceville II, Jacksonville I and Jacksonville II). This loan was a variable rate loan, such rate was based on 30-day LIBOR, which including the applicable spread equaled an interest rate of 4.67% as of October 28, 2013; however, we were required to purchase an interest rate swap with a notional amount of $45 million, and, inclusive of the interest rate swap, the effective fixed interest rate was 5.41%. For additional discussion, see "Second Restated KeyBank Loan" below. This loan was paid off in October 2013 in connection with entering into a revolving loan agreement with KeyBank National Association (the "KeyBank Revolver"). The KeyBank Revolver is further described below.

[3] The SF Bay Area - Morgan Hill loan was paid off on March 5, 2013 using proceeds from the Citi SF Bay Area - Morgan Hill Loan. For additional discussion, see "Citi SF Bay Area - Morgan Hill Loan" below.