Financial Information for Operation Segments (Parenthetical) (Detail) (Home Sales and Rentals Operations segment, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Home Sales and Rentals Operations segment
Segment Reporting Information [Line Items]
Site rental income	$ 8.9	$ 5.1	$ 16.6	$ 9.8