Reportable Segments- Consolidated Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operations revenues	$ 237,599	$ 221,817	$ 685,866	$ 644,767
Operations expenses	(123,959)	(115,062)	(343,941)	(322,456)
Income from segment operations	113,640	106,755	341,925	322,311
Interest income	1,815	1,767	5,378	5,005
Depreciation on real estate assets and rental homes	(30,493)	(29,518)	(90,849)	(87,203)
Amortization of in-place leases	(138)	(1,376)	(2,128)	(2,139)
Income (loss) from operations	84,824	77,628	254,326	237,974
Reconciliation to Consolidated net income:
Corporate interest income	159	0	164	47
Income from other investments, net	2,052	2,581	3,918	6,574
General and administrative	(7,505)	(7,653)	(23,339)	(23,315)
Property rights initiatives and other	(324)	(855)	(814)	(2,036)
Interest and related amortization	(25,027)	(25,440)	(74,728)	(76,635)
Equity in income of unconsolidated joint ventures	686	496	2,876	2,142
Consolidated net income	54,865	46,757	162,403	144,751
Total assets	3,525,847	3,470,383	3,525,847	3,470,383	$ 3,478,987
Capital improvements			87,877	87,316
Property Operations
Segment Reporting Information [Line Items]
Operations revenues	223,184	207,162	648,766	605,072
Operations expenses	(110,431)	(101,640)	(310,337)	(286,527)
Income from segment operations	112,753	105,522	338,429	318,545
Interest income	773	711	2,256	2,164
Depreciation on real estate assets and rental homes	(27,879)	(26,804)	(82,939)	(79,086)
Amortization of in-place leases	(138)	(1,376)	(2,128)	(2,139)
Income (loss) from operations	85,509	78,053	255,618	239,484
Reconciliation to Consolidated net income:
Total assets	3,298,122	3,238,699	3,298,122	3,238,699
Capital improvements			52,040	38,758
Home Sales and Rentals Operations
Segment Reporting Information [Line Items]
Operations revenues	14,415	14,655	37,100	39,695
Operations expenses	(13,528)	(13,422)	(33,604)	(35,929)
Income from segment operations	887	1,233	3,496	3,766
Interest income	1,042	1,056	3,122	2,841
Depreciation on real estate assets and rental homes	(2,614)	(2,714)	(7,910)	(8,117)
Amortization of in-place leases	0	0	0	0
Income (loss) from operations	(685)	(425)	(1,292)	(1,510)
Reconciliation to Consolidated net income:
Total assets	$ 227,725	$ 231,684	227,725	231,684
Capital improvements			$ 35,837	$ 48,558