Sonic Automotive, Inc. Quarterly report pursuant to Section 13 or 15(d)

Property and Equipment - Components of Property and Equipment, Net (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Total, at cost	$ 1,155,682us-gaap_PropertyPlantAndEquipmentGross	$ 1,115,936us-gaap_PropertyPlantAndEquipmentGross
Less accumulated depreciation	(332,543)	(316,617)
Property and equipment, net	823,139us-gaap_PropertyPlantAndEquipmentNet	799,319us-gaap_PropertyPlantAndEquipmentNet
Land [Member]
Property Plant And Equipment [Line Items]
Total, at cost	232,812	224,124
Building and Improvements [Member]
Property Plant And Equipment [Line Items]
Total, at cost	627,372	582,261
Office Equipment and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total, at cost	164,731	151,165
Parts and Service Equipment [Member]
Property Plant And Equipment [Line Items]
Total, at cost	71,774	68,248
Company Vehicles [Member]
Property Plant And Equipment [Line Items]
Total, at cost	8,969	8,958
Construction in Progress [Member]
Property Plant And Equipment [Line Items]
Total, at cost	$ 50,024	$ 81,180