Contingencies - Warranty (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014 home	Sep. 30, 2014 home
Loss Contingencies [Line Items]
Standard product warranty length, minimum			1 year
Standard product warranty length, maximum			2 years
Limited product warranty length			5 years
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 27,227,000	$ 11,911,000	$ 16,084,000	$ 11,663,000	$ 16,084,000	$ 11,663,000
Accruals for warranties issued	1,630,000	1,047,000	3,155,000	2,170,000
Changes in liability related to warranties existing in prior periods	6,524,000	1,480,000	20,754,000	3,223,000
Payments made	(6,587,000)	(1,877,000)	(11,199,000)	(4,495,000)
Balance at end of period	28,794,000	12,561,000	28,794,000	12,561,000
Insurance Recoveries	5,700,000
Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Product warranty expense			22,800,000
FLORIDA
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	16,200,000		4,000,000		4,000,000
Balance at end of period	17,200,000		17,200,000		16,200,000	4,000,000
Homes likely to require more than minor repairs			436		382	135
Homes repaired during period			65		42	11
Number of homes requiring more than minor repairs accounted for in warranty liability	340		340			124
Product warranty accrual, warranties issued	4,300,000				13,600,000	4,300,000
Product warranty accrual, payments	3,300,000				1,400,000	300,000
Insurance Recoveries	4,300,000
FLORIDA | Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Standard product warranty					8 years
Product warranty expense			22,200,000
NEW JERSEY | Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Standard product warranty			8 years
Product warranty expense			$ 600,000
Number of Communities With Water Intrusion Issues			1