Restricted Share Grants - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended		1 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	May 28, 2013 2007 Stock Option Plan [Member]	Feb. 28, 2013 2007 Stock Option Plan [Member]	Jun. 30, 2013 2007 Stock Option Plan [Member]	May 20, 2013 2007 Stock Option Plan [Member]	Jan. 31, 2013 2007 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common shares issued								600,000
Increase in shares issuable under the Trust's 2007 Stock Option Plan								500,000
Initial public offering				500,000	100,000
Increase in shares issuable under the Trust's 2007 Stock Option Plan						1,000,000	100,000
Non-cash compensation expense	$ 168,000	$ 211,000