Reportable Segments- Consolidated Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operations revenues	$ 197,566	$ 184,519	$ 403,041	$ 376,966
Operations expenses	(102,179)	(94,406)	(198,657)	(186,072)
Income from segment operations	95,387	90,113	204,384	190,894
Interest income	1,714	1,819	3,511	3,725
Depreciation on real estate assets and rental homes	(28,335)	(27,762)	(56,451)	(55,403)
Amortization of in-place leases	(669)	(1,401)	(1,334)	(2,716)
Income from operations	68,097	62,769	150,110	136,500
Reconciliation to Consolidated net income:
Corporate interest income	22	59	45	850
Income from other investments, net	2,178	2,628	3,297	4,229
General and administrative	(7,541)	(6,794)	(14,947)	(12,555)
Property rights initiatives and other	(694)	(1,001)	(1,247)	(1,312)
Early debt retirement	69	0	(16,922)	0
Interest and related amortization	(26,145)	(28,265)	(53,421)	(56,313)
Equity in income of unconsolidated joint ventures	840	644	1,724	2,531
Consolidated net income	36,826	30,040	68,639	73,930
Total assets	3,447,508	3,430,424	3,447,508	3,430,424	$ 3,446,339
Capital improvements			42,259	26,534
Property Operations
Segment Reporting Information [Line Items]
Operations revenues	184,125	173,928	378,814	357,145
Operations expenses	(90,677)	(85,984)	(177,957)	(169,805)
Income from segment operations	93,448	87,944	200,857	187,340
Interest income	713	774	1,422	1,571
Depreciation on real estate assets and rental homes	(25,586)	(24,949)	(50,965)	(49,806)
Amortization of in-place leases	(669)	(1,401)	(1,334)	(2,716)
Income from operations	67,906	62,368	149,980	136,389
Reconciliation to Consolidated net income:
Total assets	3,192,050	3,143,600	3,192,050	3,143,600
Capital improvements			22,557	13,519
Home Sales and Rentals Operations
Segment Reporting Information [Line Items]
Operations revenues	13,441	10,591	24,227	19,821
Operations expenses	(11,502)	(8,422)	(20,700)	(16,267)
Income from segment operations	1,939	2,169	3,527	3,554
Interest income	1,001	1,045	2,089	2,154
Depreciation on real estate assets and rental homes	(2,749)	(2,813)	(5,486)	(5,597)
Amortization of in-place leases	0	0	0	0
Income from operations	191	401	130	111
Reconciliation to Consolidated net income:
Total assets	$ 255,458	$ 286,824	255,458	286,824
Capital improvements			$ 19,702	$ 13,015