Noncontrolling Interest (Details 2) (2011 Plan, LTIP Units, USD $)	1 Months Ended			3 Months Ended		6 Months Ended	12 Months Ended
	May 31, 2012	Jan. 31, 2012	Apr. 30, 2011	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
Share-based compensation
Vesting period (in years)						5 years
Units forfeited (in shares)	10,875
Total fair value at the date of grant		$ 4,800,000
Volatility factor (as a percent)		55.00%	50.00%
Risk-free interest rate (as a percent)		2.10%	3.40%
Term (in years)		10 years	10 years
Units vested (in shares)						71,339	30,066
Non-cash compensation expense recognized				100,000	200,000	500,000
Unrecognized compensation expense					3,900,000	3,900,000	2,000,000
Executive officers
Share-based compensation
Units granted (in shares)		196,260	159,046
Non-employee, independent directors
Share-based compensation
Units granted (in shares)		22,380	41,395
Units forfeited (in shares)	10,875
Amount of dividend paid	8,000