Financing Activity - Additional Information (Detail) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015 Extension	Mar. 31, 2014	Jan. 08, 2014	Apr. 17, 2013	Apr. 30, 2015
Debt Instrument [Line Items]
Amount outstanding	$ 210,000,000
Revolving Credit Facility Extension Options Available	2
Repayment of outstanding amount under revolving facility	(120,000,000)	(130,000,000)
Two Thousand Fourteen Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			250,000,000
Interest expense excluding non-cash amortization of finance costs	1,300,000	900,000
Non-cash amortization of deferred financing fees	100,000
Sales Per Square Foot			500
Investment Percentage of Gross Asset Value			2.50%
Debt Instrument, Number of Loan Entered During Period			2
Two Thousand Fourteen Term Loans [Member] | Minimum [Member]
Debt Instrument [Line Items]
Capitalization Rate			6.50%
Two Thousand Fourteen Term Loans [Member] | Maximum [Member]
Debt Instrument [Line Items]
Capitalization Rate			7.50%
Two Thousand Fourteen Term Loans and Two Thousand Thirteen Revolving Facility [Member]
Debt Instrument [Line Items]
Minimum tangible net worth	75.00%
Net proceeds of equity issuances	75.00%
Maximum secured indebtedness	0.625
Funded Indebtedness Asset Value Ratio Minimum	0.60
Maximum Investments in Persons other than Subsidiaries, Consolidated Affiliates and Unconsolidated Affiliates	5.00%
Maximum Mortgages in Favor of the Borrower or any other Subsidiary	5.00%
Maximum Aggregate Value of Investments to Gross Asset Value	10.00%
Maximum Investments in Consolidation Exempt Entities to Gross Asset Value	25.00%
Maximum Projects Under Development to Gross Asset Value	15.00%
Aggregate of Consolidation Exempt Entities and Projects to Gross Asset Value	35.00%
Unencumbered Debt Yield	12.00%
Investment Percentage of Gross Asset Value	1.75
Maximum Ratio of Secured Indebtedness to Gross Asset Value	0.60
Percentage of distribution related to FFO	95.00%
REIT Taxable Income distributions	110.00%
Minimum Percentage of Total Guarantors Required to be Guarantors Based on Gross Asset Value	95.00%
Two Thousand Fourteen Term Loans and Two Thousand Thirteen Revolving Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Minimum ratio of Adjusted EBITDA to Fixed Charges	1.50
2013 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Amount outstanding	0
Unused portion of line of credit	175,000,000
Interest expense excluding non-cash amortization of finance costs	400,000	500,000
Non-cash amortization of deferred financing fees	400,000	400,000
Stated Interest Rate	1.70%
Sales Per Square Foot	500
Percentage of unused portion of the 2013 Revolving Facility	0.30%
Line of Credit Facility, Accordion Option, Minimum Incremental Increase	5,000,000
Line of Credit Facility, Accordion Option, Minimum Increase	25,000,000
Letters of Credit Outstanding, Amount	15,000,000
2013 Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Capitalization Rate	6.50%
2013 Revolving Credit Facility [Member] | Minimum [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Weighted average interest rate of Term Loan	1.50%
2013 Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Capitalization Rate	7.50%
2013 Revolving Credit Facility [Member] | Maximum [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Weighted average interest rate of Term Loan	2.05%
2013 Revolving Credit Facility [Member] | First Extension [Member]
Debt Instrument [Line Items]
Outstanding commitments	0.15%
2013 Revolving Credit Facility [Member] | Second Extension [Member]
Debt Instrument [Line Items]
Outstanding commitments	0.20%
Five Year Term Loan [Member]
Debt Instrument [Line Items]
Unsecured Debt	150,000,000		100,000,000
Debt Instrument, Interest Rate at Period End	1.63%
Term Loan Borrowing	50,000,000
Debt Instrument, Maturity Date	Jan. 31, 2019
Seven Year Term Loan [Member]
Debt Instrument [Line Items]
Unsecured Debt	100,000,000		30,000,000
Debt Instrument, Interest Rate at Period End	2.13%
Debt Instrument, Maturity Date	Jan. 31, 2021
Wells Fargo Bank , NA [Member] | 2013 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Senior Unsecured Credit Facility	400,000,000			400,000,000.0
Maximum amount available under revolving facility through accordion option	600,000,000
Wells Fargo Bank, NA and Capital One, NA [Member] | Seven Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			100,000,000
Debt Instrument, Term			7 years
Maximum amount available under revolving facility through accordion option			200,000,000
Line of Credit Facility, Accordion Option, Minimum Incremental Increase			5,000,000
Line of Credit Facility, Accordion Option, Minimum Increase			25,000,000
Line of Credit Facility, Maximum Borrowing Capacity			100,000,000.0
Line of Credit Facility, Prepayment Penalty, Next Twelve Months			3.00%
Line of Credit Facility, Prepayment Penalty, Year Two			2.00%
Line of Credit Facility, Prepayment Penalty, Year Three			1.00%
Term Loan Borrowing	70,000,000
Wells Fargo Bank, NA and US Bank N [Member] | Five Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			150,000,000.0
Debt Instrument, Term			5 years
Maximum amount available under revolving facility through accordion option			300,000,000
Line of Credit Facility, Accordion Option, Minimum Incremental Increase			5,000,000
Line of Credit Facility, Accordion Option, Minimum Increase			25,000,000
Line of Credit Facility, Maximum Borrowing Capacity			150,000,000.0
Ratio One [Member] | London Interbank Offered Rate (LIBOR) [Member] | Wells Fargo Bank , NA [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Ratio One [Member] | London Interbank Offered Rate (LIBOR) [Member] | Wells Fargo Bank, NA and Capital One, NA [Member] | Seven Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.80%
Ratio One [Member] | London Interbank Offered Rate (LIBOR) [Member] | Wells Fargo Bank, NA and US Bank N [Member] | Five Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.35%
Subsequent Event [Member] | 2013 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unused portion of line of credit					132,100,000
Letter of credit, relieved					$ 7,100,000