Reported Segments - Consolidated Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Operations revenues	$ 911,937	$ 856,280	$ 807,265
Operations expenses	(458,774)	(427,115)	(402,990)
Income from segment operations	453,163	429,165	404,275
Interest income	7,240	6,782	6,932
Depreciation on real estate assets and rental homes	(121,455)	(117,400)	(113,609)
Amortization of in-place leases	(2,231)	(3,373)	(2,358)
Income (loss) from operations	336,717	315,174	295,240
Reconciliation to Consolidated net income
Corporate interest income	340	63	98
Income from other investments, net	5,795	7,310	7,359
General and administrative	(31,737)	(31,004)	(30,644)
Early debt retirement	(2,785)
Property rights initiatives and other	(1,148)	(4,986)	(2,986)
Early debt retirement	(2,785)	0	(16,913)
Interest and related amortization	(100,570)	(102,030)	(105,731)
Equity in income of unconsolidated joint ventures	3,765	2,605	4,089
Consolidated net income	210,377	187,132	150,512
Total assets	3,610,032	3,478,987	3,400,400
Capital improvements	126,050	119,437	93,799
Property Operations Segment
Segment Reporting Information [Line Items]
Operations revenues	859,582	803,784	758,834
Operations expenses	(411,465)	(379,201)	(360,353)
Income from segment operations	448,117	424,583	398,481
Interest income	3,048	2,894	2,813
Depreciation on real estate assets and rental homes	(110,841)	(106,560)	(102,747)
Amortization of in-place leases	(2,231)	(3,373)	(2,358)
Income (loss) from operations	338,093	317,544	296,189
Reconciliation to Consolidated net income
Total assets	3,386,084	3,250,205	3,158,559
Capital improvements	76,112	57,825	51,369
Home Sales And Rentals
Segment Reporting Information [Line Items]
Operations revenues	52,355	52,496	48,431
Operations expenses	(47,309)	(47,914)	(42,637)
Income from segment operations	5,046	4,582	5,794
Interest income	4,192	3,888	4,119
Depreciation on real estate assets and rental homes	(10,614)	(10,840)	(10,862)
Amortization of in-place leases	0	0	0
Income (loss) from operations	(1,376)	(2,370)	(949)
Reconciliation to Consolidated net income
Total assets	223,948	228,782	241,841
Capital improvements	$ 49,938	$ 61,612	$ 42,430