Income per Common Share of the Trust (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest	$ 34,290	$ 22,316	$ 88,430	$ 72,048
Discontinued operations net of noncontrolling interest	133	6,383	47,142	67,999
Net income available to common shareholders	$ 34,423	$ 28,699	$ 135,572	$ 140,047
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic	147,422	135,628	146,987	124,889
Dilutive shares for long-term compensation plans	666	700	674	766
Weighted Average Number of Shares Outstanding, Diluted	148,088	136,328	147,661	125,655
Common shares [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations, Per Basic Share	$ 0.23	$ 0.16	$ 0.60	$ 0.58
Income from Discontinued Operations, Per Basic Share	$ 0.00	$ 0.05	$ 0.32	$ 0.54
Income per common share - basic	$ 0.23	$ 0.21	$ 0.92	$ 1.12
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share	$ 0.23	$ 0.16	$ 0.60	$ 0.57
Income from Discontinued Operations, Per Diluted Share	$ 0.00	$ 0.05	$ 0.32	$ 0.54
Income per common share - diluted	$ 0.23	$ 0.21	$ 0.92	$ 1.11