Debt And Lines Of Credit , Narrative - Collateralized Term Loans (Details) (USD $)	3 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended		1 Months Ended				1 Months Ended		1 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011 Collateralized term loans - CMBS [Member] properties	Mar. 31, 2012 Collateralized term loans - CMBS [Member]	Dec. 31, 2011 Collateralized term loans - CMBS [Member]	Mar. 31, 2012 Collateralized term loans - FNMA [Member]	Dec. 31, 2011 Collateralized term loans - FNMA [Member]	Jul. 31, 2011 Collateralized term loans - FNMA [Member] Collateralized term loans - PNC and FNMA [Member]	Jul. 31, 2011 Collateralized term loans - FNMA [Member] Collateralized Term Loans - May 2023 [Member]	Mar. 31, 2012 Collateralized commercial mortgage backed securities [Member] properties sites	Jul. 31, 2011 Investor spread basis points [Member] Collateralized term loans - FNMA [Member] Collateralized Term Loans - May 2023 [Member] 90-day LIBOR Index [Member]	Jul. 31, 2011 Variable facility fee basis points [Member] Collateralized term loans - FNMA [Member] Collateralized Term Loans - May 2023 [Member] 90-day LIBOR Index [Member]	May 31, 2010 Line of credit - rental home portfolio [Member] Line of Credit [Member]	May 31, 2010 Line of credit - rental home portfolio [Member] Line of Credit [Member] Prime Rate [Member]	Mar. 31, 2009 Line of credit - manufactured home floor plan facility [Member] Line of Credit [Member]	Mar. 31, 2009 Line of credit - manufactured home floor plan facility [Member] Line of Credit [Member] Prime Rate [Member]
Debt Instrument [Line Items]
Debt weighted average to maturity, length	7 years 1 month	7 years 4 months		4 years 9 months	5 years	11 years 1 month	11 years 4 months
Debt Instrument, Face Amount			$ 115,000,000					$ 367,000,000	$ 10,000,000
Stated interest rate			5.837%
Number of properties securing a debt instument (in properties)			11							96
Refinanced amount			104,800,000
Total debt	1,287,571,000	1,268,191,000		627,016,000	629,229,000	373,400,000	364,581,000			1,000,000,000
Number of sites (in sites)										35,176
Property, net book value										$ 580,200,000
Basis points											0.95%	1.72%		2.00%		1.00%
LIBOR rate term									90 days
Amortization period of principal and interest payments									30 years
Line of Credit Facility, Interest only payment term													5 years
Line of credit facility, committed term															12 months
Facility lease termination notice, term															5 years