Borrowing Arrangements - Additional Information (Detail) (USD $)	0 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	0 Months Ended	9 Months Ended			12 Months Ended	9 Months Ended			12 Months Ended	9 Months Ended		12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended		9 Months Ended		0 Months Ended			9 Months Ended
	Sep. 02, 2014	Sep. 30, 2014 Rate Property	Sep. 30, 2013	Dec. 31, 2013 Property	Sep. 30, 2014 Old Credit Facilities [Member] Property	Dec. 31, 2013 Old Credit Facilities [Member]	Sep. 02, 2014 New Credit Facilities [Member]	Sep. 30, 2014 New Credit Facilities [Member] Property	Sep. 30, 2014 Amended Line Of Credit Facility [Member]	Sep. 30, 2014 Minimum [Member]	Dec. 31, 2013 Minimum [Member] Old Credit Facilities [Member] Rate	Sep. 30, 2014 Minimum [Member] New Credit Facilities [Member]	Sep. 30, 2014 Minimum [Member] Amended Line Of Credit Facility [Member] Rate	Sep. 30, 2014 Maximum [Member]	Dec. 31, 2013 Maximum [Member] Old Credit Facilities [Member] Rate	Sep. 30, 2014 Maximum [Member] New Credit Facilities [Member]	Sep. 30, 2014 Maximum [Member] Amended Line Of Credit Facility [Member] Rate	Dec. 31, 2013 Term Loans Old Credit Facilities [Member] Rate	Sep. 30, 2014 Term Loans New Credit Facilities [Member] Rate	Dec. 31, 2013 Term Loans Minimum [Member] Old Credit Facilities [Member] Rate	Sep. 30, 2014 Term Loans Minimum [Member] New Credit Facilities [Member] Rate	Dec. 31, 2013 Term Loans Maximum [Member] Old Credit Facilities [Member] Rate	Sep. 30, 2014 Term Loans Maximum [Member] New Credit Facilities [Member] Rate	Sep. 30, 2014 R V Resort [Member] New Credit Facilities [Member] Property	Sep. 30, 2014 R V Resort [Member] Minimum [Member] New Credit Facilities [Member]	Sep. 30, 2014 R V Resort [Member] Maximum [Member] New Credit Facilities [Member]	Sep. 02, 2014 Manufactured Home [Member]	Sep. 30, 2014 Manufactured Home [Member] Old Credit Facilities [Member]	Sep. 30, 2014 Manufactured Home [Member] New Credit Facilities [Member] Property	Sep. 30, 2014 New policy [Member] Term Loans
Debt Instrument [Line Items]
Unsecured Debt		$ 200,000,000		$ 200,000,000		$ 200,000,000
Debt Instrument, Maturity Date																		Jun. 30, 2017	Jan. 10, 2020
Mortgage notes payable		2,005,942,000		1,992,368,000
Debt, Weighted Average Interest Rate		5.20%						4.54%
Payments of Debt Extinguishment Costs	5,100,000
Debt Instrument Maturity Year										2015		2034		2039		2038									2017	2018
Debt, minimum interest rate		3.90%
Debt, maximum interest rate		8.90%
Proceeds from Issuance of Long-term Debt		169,000,000	347,060,000				115,000,000	54,000,000
Debt Instrument, Term																25 years
Number of pledge properties		137		147	16			4																2					2
Carrying values of properties encumbered		2,315,000,000		2,378,000,000
Repayments of Long-term Debt					86,300,000																						53,800,000
Debt Instrument, Interest Rate, Stated Percentage					5.57%			4.64%																6.48%				4.65%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt																								13,300,000
Debt Instrument, Unamortized Discount (Premium), Net																								1,000,000
Debt instrument, interest rate based on margin over LIBOR											1.40%		1.20%		2.00%		1.65%			1.85%	1.35%	2.80%	1.95%
Derivative, Fixed Interest Rate																		1.11%	1.04%
Derivative, Basis Spread on Variable Rate																			1.35%
Debt Instrument, Interest Rate at Period End																			2.39%
Derivative, Maturity Years																		3 years												3 years
Lines of credit, borrowing capacity						380,000,000			400,000,000
Line of Credit Facility, Additional Borrowing Capacity									100,000,000
Lines of credit, maturity date						Sep. 15, 2016			Jul. 17, 2018
Lines of credit, extension option						1 year
Line of credit, facility rate											0.25%		0.20%		0.40%		0.35%
Line of Credit Facility, Commitment Fee Amount									$ 3,500,000