Noncontrolling Interest (Details 2) (2011 Plan, LTIP Units, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended	0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Jan. 03, 2013 Non-employee, independent directors	Jan. 03, 2013 Executive officers
Share-based compensation
Units granted (in shares)						14,525	173,044
Fair value at the date of grant			$ 3.3
Volatility factor (as a percent)			45.00%
Risk-free interest rate (as a percent)			1.97%
Expected annual dividend yield (as a percent)			6.00%
Term			10 years
Units redeemed (in shares)			1,656
Units vested (in shares)			200,741		112,506
Non-cash compensation expense recognized	0.4	0.2	1.2	0.7
Unrecognized compensation expense	$ 5.6		$ 5.6		$ 3.5