Credit Facilities and Mortgage Notes Payable - Richmond Credit Facility - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended							6 Months Ended	1 Months Ended	6 Months Ended			6 Months Ended
	Aug. 31, 2014 Subsequent Event [Member] Richmond Credit Facility [Member]	Jun. 30, 2014 Maximum [Member] Libor Rate [Member]	Jun. 30, 2014 Maximum [Member] Base Rate [Member]	Jun. 30, 2014 Minimum [Member] Libor Rate [Member]	Jun. 30, 2014 Minimum [Member] Base Rate [Member]	Jan. 31, 2013 Richmond Credit Facility [Member]	Dec. 31, 2012 Richmond Credit Facility [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Third Amendment [Member]	Aug. 31, 2014 Richmond Credit Facility [Member] Subsequent Event [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Maximum [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Maximum [Member] Libor Rate [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Maximum [Member] Base Rate [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Minimum [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Minimum [Member] Libor Rate [Member]	Jun. 30, 2014 Richmond Credit Facility [Member] Minimum [Member] Base Rate [Member]
Debt Instrument [Line Items]
Credit Facility maximum borrowing capacity						$ 100	$ 80
Credit facility, maturity date								Jun. 30, 2019
Decrease in total revolving credit commitments										100			80
Increased borrowing capacity after considering accordion feature										200
Leverage Ratio		2.85%	1.85%	2.10%	1.10%						2.85%	1.85%		2.10%	1.10%
Amount of unsecured revolving credit facility expanded	40								40
Current revolving Credit facility	$ 120								$ 120