Incentive Plans (Details Textual) (USD $) Share data in Millions, unless otherwise specified	6 Months Ended				3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Apr. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2014 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2.6		5.3	0.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized					$ 6,700,000		$ 6,700,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition							1 year 6 months
Allocated Share-based Compensation Expense					500,000	600,000	800,000	1,100,000	100,000	100,000
Amortization of restricted stock awards and operating partnership units	1,629,000				400,000	200,000	800,000	400,000	100,000	200,000
Stock Granted, Value, Share-based Compensation, Net of Forfeitures, Total		$ 0			$ 11,000	$ 16,000,000	$ 200,000	$ 300,000	$ 0