Segment Reporting Identifiable Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Investment property, net	$ 5,573,825	$ 5,469,481
Cash and cash equivalents	137,448	8,164	$ 69,829	$ 45,086
Inventory of manufactured homes	25,741	21,632
Notes and other receivables, net	145,760	81,179
Collateralized receivables, net	134,015	143,870
Other assets	141,047	146,450
TOTAL ASSETS	6,157,836	5,870,776
Real Property Operations Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Investment property, net	5,112,302	5,019,165
Cash and cash equivalents	124,434	3,705
Inventory of manufactured homes	0	0
Notes and other receivables, net	132,748	68,901
Collateralized receivables, net	134,015	143,870
Other assets	137,303	143,650
TOTAL ASSETS	5,640,802	5,379,291
Home Sales and Home Rentals Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Investment property, net	461,523	450,316
Cash and cash equivalents	13,014	4,459
Inventory of manufactured homes	25,741	21,632
Notes and other receivables, net	13,012	12,278
Collateralized receivables, net	0	0
Other assets	3,744	2,800
TOTAL ASSETS	$ 517,034	$ 491,485