Reportable Segments - Income from Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Rental income									$ 879,635	$ 821,114	$ 768,416
Membership upgrade sales current period, gross									19,111	15,191
Other income									43,063	51,935	47,599
Total revenues	$ 258,640	$ 271,160	$ 248,366	$ 259,090	$ 243,451	$ 256,675	$ 240,502	$ 246,025	1,037,256	986,653	925,312
Expenses:
Real estate taxes									62,338	55,892	55,010
Sales and marketing, gross									15,583	12,542	11,438
Membership sales commissions, deferred, net									(1,219)	(813)	(354)
Total expenses									802,596	765,206	718,700
Income before equity in income of unconsolidated joint ventures									287,167	221,447	206,612
Annual membership subscriptions
Revenues:
Membership upgrade sales current period, gross									51,015	47,778	45,798
Membership upgrade sales current period, gross
Revenues:
Membership upgrade sales current period, gross									19,111	15,191	14,132
Membership upgrade sales upfront payments, deferred, net
Revenues:
Membership upgrade sales current period, gross									(10,451)	(7,380)	(4,108)
Property management
Expenses:
Cost of home sales									56,509	53,736	51,252
Home Sales
Revenues:
Membership upgrade sales current period, gross									34,655	36,064	36,302
Expenses:
Cost of home sales									35,096	37,475	36,513
Property Operations
Revenues:
Rental income									864,701	806,785	754,072
Other income											47,599
Total revenues									969,560	916,565	859,582
Expenses:
Property operating and maintenance									327,917	313,003	294,119
Real estate taxes									62,338	55,892	55,010
Sales and marketing, gross									15,583	12,542	11,438
Membership sales commissions, deferred, net									(1,219)	(813)	(354)
Total expenses									461,128	434,360	411,465
Income before equity in income of unconsolidated joint ventures									508,432	482,205	448,117
Property Operations | Annual membership subscriptions
Revenues:
Membership upgrade sales current period, gross									51,015	47,778	45,798
Property Operations | Membership upgrade sales current period, gross
Revenues:
Membership upgrade sales current period, gross									19,111	15,191	14,132
Property Operations | Membership upgrade sales upfront payments, deferred, net
Revenues:
Membership upgrade sales current period, gross									(10,451)	(7,380)	(4,108)
Property Operations | Ancillary services revenues, net
Revenues:
Membership upgrade sales current period, gross									2,121	2,256	2,089
Property Operations | Property management
Expenses:
Cost of home sales									56,509	53,736	51,252
Home Sales and Rentals Operations
Revenues:
Rental home income									14,934	14,329	14,344
Total revenues									50,961	51,721	52,355
Expenses:
Property operating and maintenance									5,603	6,836	6,610
Home selling expenses									4,401	4,095	4,186
Total expenses									45,100	48,406	47,309
Income before equity in income of unconsolidated joint ventures									5,861	3,315	5,046
Home Sales and Rentals Operations | Ancillary services revenues, net
Revenues:
Membership upgrade sales current period, gross									0	38	474
Home Sales and Rentals Operations | Home Sales
Revenues:
Membership upgrade sales current period, gross									34,655	36,064	36,302
Expenses:
Cost of home sales									35,096	37,475	36,513
Home Sales and Rentals Operations | Brokered resale revenues, net
Revenues:
Membership upgrade sales current period, gross									$ 1,372	$ 1,290	$ 1,235