Reportable Segments - Income from Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Community base rental income									$ 489,613	$ 464,745	$ 442,046
Resort base rental income									218,806	201,533	184,760
Right-to-use annual payments									45,798	45,035	44,443
Right-to-use contracts current period, gross									14,132	12,327	12,783
Right-to-use contract upfront payments, deferred, net									(4,108)	(3,079)	(4,231)
Utility and other income									93,252	81,427	76,153
Gross revenue from home sales									36,302	37,191	33,150
Brokered resale revenues and ancillary services revenues, net									3,798	2,994	4,149
Rental home income									14,344	14,107	14,012
Total revenues	$ 229,986	$ 241,625	$ 221,312	$ 232,389	$ 214,042	$ 226,165	$ 210,081	$ 220,147	925,312	870,435	821,654
Expenses:
Property operating and maintenance									294,119	268,249	254,668
Real estate taxes									55,010	53,036	50,962
Sales and marketing, gross									11,438	11,056	11,751
Right-to-use contract commissions, deferred, net									(354)	(223)	(1,556)
Property management									51,252	47,083	44,528
Cost of home sales									36,513	37,456	32,279
Home selling expenses									4,186	3,575	3,191
Rental home operating and maintenance									6,610	6,883	7,167
Total property operations expenses									718,700	685,908	675,231
Income before equity in income of unconsolidated joint ventures									206,612	184,527	146,423
Property Operations Segment
Revenues:
Community base rental income									489,613	464,745	442,046
Resort base rental income									218,806	201,533	184,760
Right-to-use annual payments									45,798	45,035	44,443
Right-to-use contracts current period, gross									14,132	12,327	12,783
Right-to-use contract upfront payments, deferred, net									(4,108)	(3,079)	(4,231)
Utility and other income									93,252	81,427	76,153
Ancillary services revenues, net									2,089	1,796	2,880
Total revenues									859,582	803,784	758,834
Expenses:
Property operating and maintenance									294,119	268,249	254,668
Real estate taxes									55,010	53,036	50,962
Sales and marketing, gross									11,438	11,056	11,751
Right-to-use contract commissions, deferred, net									(354)	(223)	(1,556)
Property management									51,252	47,083	44,528
Total property operations expenses									411,465	379,201	360,353
Income before equity in income of unconsolidated joint ventures									448,117	424,583	398,481
Home Sales And Rentals
Revenues:
Gross revenue from home sales									36,302	37,191	33,150
Brokered resale revenues and ancillary services revenues, net									1,235	1,198	1,269
Rental home income									14,344	14,107	14,012
Ancillary Services Revenues									474	0	0
Total revenues									52,355	52,496	48,431
Expenses:
Cost of home sales									36,513	37,456	32,279
Home selling expenses									4,186	3,575	3,191
Rental home operating and maintenance									6,610	6,883	7,167
Total property operations expenses									47,309	47,914	42,637
Income before equity in income of unconsolidated joint ventures									$ 5,046	$ 4,582	$ 5,794