Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Mar. 07, 2016	Jun. 30, 2015
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	WLH
Entity Registrant Name	WILLIAM LYON HOMES
Entity Central Index Key	0001095996
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Status	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 512.5
Common stock, Class A, par value $0.01 per share; 150,000,000 shares authorized; 28,363,879 and 28,073,438 shares issued, 27,657,435 and 27,487,257 shares outstanding at December 31, 2015 and 2014, respectively
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		27,855,561
Common stock, Class B, par value $0.01 per share; 30,000,000 shares authorized; 3,813,884 shares issued and outstanding at December 31, 2015 and 2014, respectively
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		3,813,884