Reportable Segments Reported Segments - Consolidated Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operations revenues	$ 807,265	$ 761,409	$ 713,273
Operations expenses	402,990	381,597	356,323
Income from segment operations	404,275	379,812	356,950
Interest income	6,932	7,450	7,770
Depreciation on real estate assets and rental homes	113,609	111,065	108,229
Amortization of in-place leases	2,358	3,999	1,940
Income (loss) from operations	295,240	272,198	254,551
Reconciliation to Consolidated net income
Corporate interest income	98	897	490
Income from other investments, net	7,359	7,053	7,515
General and administrative	30,644	27,410	28,211
Property rights initiatives and other	2,986	2,923	2,771
Early debt retirement	16,913	5,087	37,844
Interest and related amortization	105,731	112,295	118,522
Equity in income of unconsolidated joint ventures	4,089	4,578	2,039
Gain on sale of property	0	1,457	0
Gain on sale of property, net of tax	0	0	41,525
Income from discontinued operations before gain on sale of property	0	0	7,133
Consolidated net income	150,512	138,468	125,905
Total assets	3,420,061	3,446,339	3,392,309
Capital improvements	93,799	63,721	64,714
Property Operations Segment
Segment Reporting Information [Line Items]
Operations revenues	758,834	716,942	679,992
Operations expenses	360,353	345,067	329,468
Income from segment operations	398,481	371,875	350,524
Interest income	2,813	2,984	3,397
Depreciation on real estate assets and rental homes	102,747	99,980	101,374
Amortization of in-place leases	2,358	3,999	1,940
Income (loss) from operations	296,189	270,880	250,607
Reconciliation to Consolidated net income
Total assets	3,177,531	3,178,883	3,096,826
Capital improvements	51,369	35,973	26,430
Home Sales And Rentals
Segment Reporting Information [Line Items]
Operations revenues	48,431	44,467	33,281
Operations expenses	42,637	36,530	26,855
Income from segment operations	5,794	7,937	6,426
Interest income	4,119	4,466	4,373
Depreciation on real estate assets and rental homes	10,862	11,085	6,855
Amortization of in-place leases	0	0	0
Income (loss) from operations	(949)	1,318	3,944
Reconciliation to Consolidated net income
Total assets	242,530	267,456	295,483
Capital improvements	$ 42,430	$ 27,748	$ 38,284