Commitments And Contingencies (Other Contingencies) (Detail) (USD $)	12 Months Ended	3 Months Ended			12 Months Ended	0 Months Ended	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2011	Dec. 31, 2008	Dec. 31, 2013	Aug. 08, 2014	Dec. 31, 2011 Home Homeowner	Mar. 31, 2015	Dec. 31, 2007	Jul. 31, 2006	Dec. 31, 2012 acre	Apr. 15, 2011 Homeowner
Loss Contingencies [Line Items]
Airplane operating lease period, years	5
Fair value of residual value guarantee		$ 7,800,000
Fair Value Of Residual Value Guarantee, Fair Value of Operating Lease Asset Threshold		9,500,000
Environmental Claims For A Site In Goodyear Arizona
Loss Contingencies [Line Items]
Estimated liability				65,200,000				75,600,000	41,500,000
Amount of additional remediation activities		49,000,000	30,300,000	24,300,000
Accrued environmental loss contingencies current								15,500,000
Loss contingency reimbursement rate										21.00%
Other receivables								17,100,000
Environmental Claims For Crab Orchard National Wildlife Refuge Superfund Site
Loss Contingencies [Line Items]
Approximate size of referenced site, acres											55,000
amount paid into escrow					166,667
Environmental Claims For Site In Roseland New Jersey
Loss Contingencies [Line Items]
Amount of additional remediation activities		6,800,000
Approximate number of homes tested for contaminants							40
Number of Homes Where Contaminants Were Found							3
Homeowners Filing Suits Against Company					139							3
Homes Suing Company Where Vapor Mitigation Equipment Was Installed					3
Loss Contingency, Damages Paid, Value						$ 6,500,000
Number Of Tenants Who Filed Separate Lawsuit												1
Number of members in the purported class							138