Financial Information for Operation Segments (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Community base rental income	$ 103,157,000	$ 98,752,000	$ 305,401,000	$ 295,185,000
Resort base rental income	39,932,000	36,516,000	113,868,000	104,503,000
Right-to-use annual payments	12,323,000	12,115,000	35,889,000	36,087,000
Right-to-use contracts current period, gross	3,707,000	4,494,000	9,899,000	9,680,000
Right-to-use contracts current period, deferred	(1,856,000)	(2,788,000)	(4,446,000)	(4,680,000)
Utility And Other Income	16,224,000	15,499,000	48,694,000	48,559,000
Gross revenue from home sales	5,415,000	1,660,000	12,328,000	5,585,000
Brokered resale revenues, net	1,395,000	990,000	4,122,000	3,211,000
Rental home income	3,584,000	3,055,000	10,576,000	8,422,000
Total revenues	187,966,000	175,064,000	548,493,000	518,392,000
Expenses:
Property operating and maintenance	61,782,000	58,586,000	175,183,000	168,444,000
Real estate taxes	11,584,000	11,362,000	35,873,000	34,729,000
Sales and marketing, gross	3,842,000	3,573,000	9,536,000	7,848,000
Sales and marketing, deferred commissions, net	(706,000)	(1,277,000)	(1,824,000)	(2,174,000)
Property management	10,077,000	9,358,000	30,380,000	28,305,000
Cost of home sales	5,137,000	1,804,000	11,837,000	6,485,000
Home selling expenses	563,000	325,000	1,544,000	1,051,000
Rental home operating and maintenance	1,950,000	1,713,000	5,307,000	4,407,000
Total expenses	195,037,000	156,548,000	501,687,000	477,698,000
Income from operations	(7,071,000)	18,516,000	46,806,000	40,694,000
Property Operations Segment [Member]
Revenues:
Community base rental income	103,157,000	98,752,000	305,401,000	295,185,000
Resort base rental income	39,932,000	36,516,000	113,868,000	104,503,000
Right-to-use annual payments	12,323,000	12,115,000	35,889,000	36,087,000
Right-to-use contracts current period, gross	3,707,000	4,494,000	9,899,000	9,680,000
Right-to-use contracts current period, deferred	(1,856,000)	(2,788,000)	(4,446,000)	(4,680,000)
Utility And Other Income	16,224,000	15,499,000	48,694,000	48,559,000
Ancillary services revenues, net	1,170,000	732,000	3,282,000	2,294,000
Total revenues	174,657,000	165,320,000	512,587,000	491,628,000
Expenses:
Property operating and maintenance	61,782,000	58,586,000	175,183,000	168,444,000
Real estate taxes	11,584,000	11,362,000	35,873,000	34,729,000
Sales and marketing, gross	3,842,000	3,573,000	9,536,000	7,848,000
Sales and marketing, deferred commissions, net	(706,000)	(1,277,000)	(1,824,000)	(2,174,000)
Property management	10,077,000	9,358,000	30,380,000	28,305,000
Total expenses	86,579,000	81,602,000	249,148,000	237,152,000
Income from operations	88,078,000	83,718,000	263,439,000	254,476,000
Home Sales and Rentals Operations segment
Segment Reporting Information [Line Items]
Site Rental Income	9,700,000	8,400,000	28,900,000	23,700,000
Revenues:
Gross revenue from home sales	5,415,000	1,660,000	12,328,000	5,585,000
Brokered resale revenues, net	225,000	258,000	840,000	917,000
Rental home income	3,584,000	3,055,000	10,576,000	8,422,000
Total revenues	9,224,000	4,973,000	23,744,000	14,924,000
Expenses:
Cost of home sales	5,137,000	1,804,000	11,837,000	6,485,000
Home selling expenses	563,000	325,000	1,544,000	1,051,000
Rental home operating and maintenance	1,950,000	1,713,000	5,307,000	4,407,000
Total expenses	7,650,000	3,842,000	18,688,000	11,943,000
Income from operations	$ 1,574,000	$ 1,131,000	$ 5,056,000	$ 2,981,000