Restricted Share Grants - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended	1 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	May 28, 2013 2007 Stock Option Plan [Member]	Feb. 28, 2013 2007 Stock Option Plan [Member]	Sep. 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 by shareholders							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	$ 346	$ 557
Restricted Shares forfeited		0