Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended				6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	May 31, 2013 Class A Common Stock [Member]	Jun. 30, 2013 REIT [Member]	Dec. 31, 2012 Total Capital Loss Carryforwards [Member]	Dec. 31, 2012 Capital Loss Carryforwards Expiring 2013 [Member]	Dec. 31, 2012 Capital Loss Carryforwards Expiring 2014 [Member]	Dec. 31, 2012 Capital Loss Carryforwards Expiring 2015 [Member]	Dec. 31, 2012 Capital Loss Carryforwards Expiring 2017 [Member]
Annual distribution of net taxable income for U.S. federal income tax not to apply to our earnings that we distribute (percent)		90.00%
Net taxable income subject to distribution (percent)		100.00%
Excise tax rate		4.00%
Income tax provision	$ 554,000	$ 593,000	$ 301,000			$ 554,000
Common stock, shares issued	28,802,000	28,802,000		2,927,000	25,875,000
Net operating loss carried forward				161,500,000
Net capital losses carried forward							$ 121,400,000	$ 2,000,000	$ 87,400,000	$ 31,400,000	$ 618,000
NOL expiration date		Expires in 2029