Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended	0 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2012 Restricted Stock	Jun. 30, 2013 Restricted Stock	Jun. 30, 2012 Restricted Stock	Jun. 30, 2013 2006 Incentive Plan	Jun. 30, 2013 General and Administrative Expense Restricted Stock	Jun. 30, 2013 General and Administrative Expense Restricted Stock	Jun. 30, 2012 Listing Expenses Restricted Stock	Jun. 30, 2013 Listing Expenses Restricted Stock	Jun. 30, 2012 Listing Expenses Restricted Stock	Jun. 30, 2012 Non Traded REIT Expenses Restricted Stock	Jun. 30, 2012 Non Traded REIT Expenses Restricted Stock	Jan. 07, 2013 Common Stock Offering	Jun. 30, 2013 Common Stock Offering	Jun. 30, 2013 Long Term Incentive Program Listing Expenses	Jun. 30, 2012 Long Term Incentive Program Listing Expenses	Jun. 30, 2013 Long Term Incentive Program Listing Expenses	Jun. 30, 2012 Long Term Incentive Program Listing Expenses	Jun. 30, 2013 Long Term Incentive Program Change in Control of Company
Common Stock Offerings [Abstract]
Maximum amount of common stock authorized												$ 250.0
Issuance of common stock (in shares)													11,042,934
Average share price													$ 11.53
Long-Term Incentive Program [Abstract]
Number of shares authorized (in shares)				10,000,000
Number of shares available for grant (in shares)				5,095,500
Allocated share-based compensation expense	5.2	1.5	6.2		0.3	0.9	4.7	0.6	4.7	0.5	1.5			0	1.5	3.1	1.5
Nonvested awards, total compensation cost not yet recognized		$ 4.4																$ 4.5
Contingent units																		450,000
Period for recognition		2 years 4 months 24 days