Incentive Plans (Details Textual) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2.5
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0.3	1.2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 6,900,000
Amortization of restricted stock awards and operating partnership units	3,300,000	2,252,000	842,000
Restricted Stock [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 3 months 18 days
Allocated Share-based Compensation Expense	1,900,000	1,000,000	200,000
Amortization of restricted stock awards and operating partnership units	900,000	600,000
Stock Granted, Value, Share-based Compensation, Net of Forfeitures, Total	500,000	100,000	100,000
Restricted Stock Units (RSUs) [Member]
Allocated Share-based Compensation Expense	200,000	200,000	100,000
Amortization of restricted stock awards and operating partnership units	$ 300,000	$ 400,000	$ 500,000