Equity Incentive Plan - Amortization of Restricted Stock (Details) (General and Administrative Expenses, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Equity Incentive Plan
Total Equity Compensation Expense	$ 1.8	$ 1.1
Restricted stock
Equity Incentive Plan
Total Equity Compensation Expense	0.5	0.3
LTIP Units
Equity Incentive Plan
Total Equity Compensation Expense	1.1	0.6
OPP Awards
Equity Incentive Plan
Total Equity Compensation Expense	0.1	0.1
Directors
Equity Incentive Plan
Total Equity Compensation Expense	$ 0.1	$ 0.1