Summary of Significant Accounting Policies - Additional Information 1 (Detail) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Unsecured Revolving Credit Facility [Member]	Jun. 30, 2013 Unsecured Revolving Credit Facility [Member]	Jun. 30, 2014 Unsecured Revolving Credit Facility [Member]	Jun. 30, 2013 Unsecured Revolving Credit Facility [Member]	Jun. 30, 2013 Richmond Credit Facility [Member]	Jun. 30, 2014 Interest Rate Swap [Member] Cash Flow Hedging [Member]	Feb. 29, 2012 Interest Rate Swap [Member] Cash Flow Hedging [Member]	Feb. 08, 2012 Interest Rate Swap [Member] Cash Flow Hedging [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment losses	$ 0	$ 0	$ 0	$ 0
Amortization of the deferred financing costs			1,314,000			600,000	700,000	1,200,000	1,600,000
Written off unamortized debt cost							2,000,000			100,000
Written off unamortization cost relation to assets securitization				1,300,000
Amortization of deferred leasing costs totaled	1,500,000	1,000,000	2,800,000	2,100,000
Deferred income	8,177,000		8,177,000		7,892,000
Amortization of deferred revenue	1,200,000	1,100,000	2,400,000	2,200,000
Notional amount of derivative											50,000,000	150,000,000	150,000,000
Company recorded equity-based compensation expense net of repurchased awards	1,100,000	400,000	2,000,000	800,000
Amount of the straight-line rent receivable on the balance sheets included in rents and other receivables	$ 3,200,000		$ 3,200,000		$ 2,900,000