Subsequent Events - Additional Information (Detail) (USD $)	6 Months Ended		1 Months Ended				0 Months Ended	1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	May 13, 2013 Operating Partnership	Jul. 11, 2013 Subsequent Event	Jul. 30, 2013 Subsequent Event Construction Loans	Jul. 29, 2013 Subsequent Event Construction Loans	Jul. 16, 2013 Subsequent Event Operating Partnership	Jul. 16, 2013 Subsequent Event Operating Partnership
Subsequent Event [Line Items]
Revolving credit facility, borrowed amount			$ 40,000,000				$ 15,000,000	$ 15,000,000
Construction loan					63,000,000	63,000,000
Dividends paid	$ 12,927,000	$ 8,629,000		$ 2,600,000