Reported Segments - Consolidated Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operations revenues	$ 856,280	$ 807,265	$ 761,409
Operations expenses	(427,115)	(402,990)	(381,597)
Income from segment operations	429,165	404,275	379,812
Interest income	6,782	6,932	7,450
Depreciation on real estate assets and rental homes	(117,400)	(113,609)	(111,065)
Amortization of in-place leases	(3,373)	(2,358)	(3,999)
Income (loss) from operations	315,174	295,240	272,198
Reconciliation to Consolidated net income
Corporate interest income	63	98	897
Income from other investments, net	7,310	7,359	7,053
General and administrative	(31,004)	(30,644)	(27,410)
Property rights initiatives and other	(4,986)	(2,986)	(2,923)
Early debt retirement	0	(16,913)	(5,087)
Interest and related amortization	(102,030)	(105,731)	(112,295)
Equity in income of unconsolidated joint ventures	2,605	4,089	4,578
Gain on sale of property			1,457
Consolidated net income	187,132	150,512	138,468
Total assets	3,478,987	3,400,400	3,429,225
Capital improvements	119,437	93,799	63,721
Property Operations Segment
Segment Reporting Information [Line Items]
Operations revenues	803,784	758,834	716,942
Operations expenses	(379,201)	(360,353)	(345,067)
Income from segment operations	424,583	398,481	371,875
Interest income	2,894	2,813	2,984
Depreciation on real estate assets and rental homes	(106,560)	(102,747)	(99,980)
Amortization of in-place leases	(3,373)	(2,358)	(3,999)
Income (loss) from operations	317,544	296,189	270,880
Reconciliation to Consolidated net income
Total assets	3,250,205	3,158,559	3,161,769
Capital improvements	57,825	51,369	35,973
Home Sales And Rentals
Segment Reporting Information [Line Items]
Operations revenues	52,496	48,431	44,467
Operations expenses	(47,914)	(42,637)	(36,530)
Income from segment operations	4,582	5,794	7,937
Interest income	3,888	4,119	4,466
Depreciation on real estate assets and rental homes	(10,840)	(10,862)	(11,085)
Amortization of in-place leases	0	0	0
Income (loss) from operations	(2,370)	(949)	1,318
Reconciliation to Consolidated net income
Total assets	228,782	241,841	267,456
Capital improvements	$ 61,612	$ 42,430	$ 27,748