Segment Information (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of consolidated net operating income
Consolidated net operating income									$ 340,441	$ 324,831	$ 321,777
Less:
Interest expense									(121,937)	(132,939)	(131,405)
Interest expense - amortization of deferred financing costs									(4,676)	(6,208)	(4,991)
Interest expense — financing obligation									(972)	(850)	0
Depreciation and amortization									(197,021)	(188,382)	(202,933)
Administrative expenses									(27,628)	(25,413)	(24,602)
Plus:
Interest income									1,044	3,008	1,810
Historic tax credit transaction income									11,853	11,840	12,026
Recognized hedge activity									0	(2,985)	0
Equity in income of real estate ventures									3,664	2,741	3,775
Net gain from remeasurement of investments in real estate ventures									6,866	0	0
Net gain on sale of interests in real estate									0	0	2,985
Net gain (loss) on sale of undepreciated real estate									(137)	0	0
Net gain (loss) on real estate venture transactions									29,604	(950)	(222)
Gain (loss) on early extinguishment of debt									(2,119)	(22,002)	(2,776)
Income (loss) from continuing operations									38,982	(37,309)	(24,556)
Income from discontinued operations									4,207	43,838	19,841
Net income (loss)	$ 21,002	$ 11,088	$ 7,180	$ 3,919	$ (26,698)	$ 17,089	$ 6,802	$ 9,336	$ 43,189	$ 6,529	$ (4,715)