Summary of Quarterly Results (Tables)

12 Months Ended

Dec. 31, 2015

Summary of Quarterly Results (Unaudited) [Abstract]

Schedule Of Quarterly Financial Information [Table Text Block]

(Amounts in thousands, except per share amounts)				Net Income
				Attributable		Net Income Per
				to Common		Common Share (2)
		Revenues		Shareholders (1)		Basic		Diluted
2015
	December 31	$	651,581	$	230,742	$	1.22	$	1.22
	September 30		627,596		198,870		1.05		1.05
	June 30		616,288		165,651		0.88		0.87
	March 31		606,802		84,593		0.45		0.45
2014
	December 31	$	597,010	$	513,238	$	2.73	$	2.72
	September 30		578,710		131,159		0.70		0.69
	June 30		574,411		76,642		0.41		0.41
	March 31		562,381		62,349		0.33		0.33
(1)	Fluctuations among quarters resulted primarily from non-cash impairment losses, mark-to-market of derivative instruments, net gains on sale of real estate and from seasonality of business operations.
(2)	The total for the year may differ from the sum of the quarters as a result of weighting.