Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012
Accounting Policies [Abstract]
Restricted common shares issued		600,000
Quarterly dividend paid per Common Share	$ 0.1625	$ 0.325	$ 0.325
Quarterly dividend paid per Series D Preferred Share	$ 0.578125	$ 1.15625	$ 1.15625