Reported Segments - Consolidated Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operations revenues	$ 968,286	$ 911,937	$ 856,280
Operations expenses	(482,766)	(458,774)	(427,115)
Income from segment operations	485,520	453,163	429,165
Interest income	7,272	7,240	6,782
Depreciation on real estate assets and rental homes	(130,022)	(121,455)	(117,400)
Amortization of in-place leases	(7,187)	(2,231)	(3,373)
Income (loss) from operations	355,583	336,717	315,174
Reconciliation to consolidated net income
Corporate interest income	253	340	63
Income from other investments, net	10,842	5,795	7,310
General and administrative	(37,684)	(31,737)	(31,004)
Early debt retirement	(1,071)	(2,785)	0
Other expenses	(1,483)	(1,148)	(4,986)
Interest and related amortization	(104,993)	(100,570)	(102,030)
Equity in income of unconsolidated joint ventures	4,939	3,765	2,605
Consolidated net income	226,386	210,377	187,132
Total assets	3,925,808	3,610,032	3,478,987
Capital improvements	181,622	126,050	119,437
Property Operations
Segment Reporting Information [Line Items]
Operations revenues	916,565	859,582	803,784
Operations expenses	(434,360)	(411,465)	(379,201)
Income from segment operations	482,205	448,117	424,583
Interest income	3,374	3,048	2,894
Depreciation on real estate assets and rental homes	(120,212)	(110,841)	(106,560)
Amortization of in-place leases	(7,187)	(2,231)	(3,373)
Income (loss) from operations	358,180	338,093	317,544
Reconciliation to consolidated net income
Total assets	3,692,510	3,386,084	3,250,205
Capital improvements	94,015	76,112	57,825
Home Sales and Rentals Operations
Segment Reporting Information [Line Items]
Operations revenues	51,721	52,355	52,496
Operations expenses	(48,406)	(47,309)	(47,914)
Income from segment operations	3,315	5,046	4,582
Interest income	3,898	4,192	3,888
Depreciation on real estate assets and rental homes	(9,810)	(10,614)	(10,840)
Amortization of in-place leases	0	0	0
Income (loss) from operations	(2,597)	(1,376)	(2,370)
Reconciliation to consolidated net income
Total assets	233,298	223,948	228,782
Capital improvements	$ 87,607	$ 49,938	$ 61,612