Property Dispositions (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Disposal Group, Including Discontinued Operation, Income Statement Disclosures
Revenues	$ 109,185	$ 109,667	$ 216,411	$ 208,417
Expenses	(60,037)	(53,795)	(116,242)	(107,903)
Gain on sale of real estate, net of tax	25,017	0	50,415	2,197
Income before gain on sale of real estate	66,224	39,375	96,443	61,022
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Disposal Group, Including Discontinued Operation, Income Statement Disclosures
Revenues	4,282	5,752	10,396	11,352
Expenses	(3,255)	(5,095)	(8,239)	(10,394)
Gain on sale of real estate, net of tax	25,017	0	50,415	2,197
Loss on extinguishment of debt	(5,091)	0	(7,590)	0
Income before gain on sale of real estate	$ 20,953	$ 657	$ 44,982	$ 3,155