Borrowing Arrangements -2017 activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) property loan	Dec. 31, 2016 USD ($) property integer	Dec. 31, 2015 USD ($) property	Dec. 31, 2015 property loan	Dec. 31, 2015 property integer
Debt Instrument [Line Items]
Number of loans	3			4	2
Proceeds from issuance of secured debt | $	$ 146,000	$ 88,100
Mortgage notes payable financing proceeds | $	$ 350,369	$ 88,050	$ 395,323
Stated interest rate (in percentage)	4.07%
Debt instrument, term (in years)	20 years
Number of pledged properties	120	126
Number Of pledged properties, loans repaid	15
Number of pledged properties, maturing loan | loan	13
Repayments of debt | $	$ 230,200
Penalty on prepayment | $	$ 2,700
Interest rate at period end (in percentage)	5.93%	4.01%
Old Credit Facilities
Debt Instrument [Line Items]
Number of pledged properties			32	32	32
Repayments of debt | $		$ 41,800
Interest rate at period end (in percentage)		5.85%
Fannie Mae
Debt Instrument [Line Items]
Stated interest rate (in percentage)	3.97%
Number of pledged properties	5
Fannie Mae | Secured Debt | Line of Credit
Debt Instrument [Line Items]
Debt instrument, face amount | $	$ 204,400
Manufactured homes
Debt Instrument [Line Items]
Number of pledged properties towards loans repaid		4
Manufactured homes | Old Credit Facilities
Debt Instrument [Line Items]
Number of pledged properties			1	1	1
Number of pledged properties towards loans repaid	13	3
R V Resort
Debt Instrument [Line Items]
Number of pledged properties towards loans repaid		2
R V Resort | Old Credit Facilities
Debt Instrument [Line Items]
Number of pledged properties			3	3	3
Number of pledged properties towards loans repaid	2	2
Paradise Park Largo
Debt Instrument [Line Items]
Stated interest rate (in percentage)	4.60%
Debt assumed for the purchase of property | $	$ 5,900