Sonic Automotive, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Capital Structure and Per Share Data - Additional Information (Detail)

Capital Structure and Per Share Data - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Vote	Dec. 31, 2013	Dec. 31, 2012
Capital Structure And Per Share Data [Line Items]
Preferred stock shares authorized	3,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Preferred stock, outstanding	0us-gaap_PreferredStockSharesOutstanding	0us-gaap_PreferredStockSharesOutstanding
Number of classes of common stock	2sah_NumberOfClassesOfCommonStock
Stated interest rate on debt agreement	5.00%
5.0% Convertible Senior Notes [Member]
Capital Structure And Per Share Data [Line Items]
Stated interest rate on debt agreement	5.00%	5.00%	5.00%
Class A Convertible Preferred Stock [Member]
Capital Structure And Per Share Data [Line Items]
Preferred stock shares authorized	300,000
Preferred Stock Par Value	$ 0.10
Class A convertible preferred stock shares redeemed	13,802
Class A convertible preferred stock redemption price	$ 1,000
Series I Preferred Stock [Member]
Capital Structure And Per Share Data [Line Items]
Class A Convertible Preferred Stock Shares Authorized	100,000
Series II Preferred Stock [Member]
Capital Structure And Per Share Data [Line Items]
Class A Convertible Preferred Stock Shares Authorized	100,000
Series III Preferred Stock [Member]
Capital Structure And Per Share Data [Line Items]
Class A Convertible Preferred Stock Shares Authorized	100,000
Common Class A [Member]
Capital Structure And Per Share Data [Line Items]
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, number of votes per share	1
Number of shares of class A common stock issuable against each share of class B common stock	1
Authorized amount expend on repurchase of shares	$ 495.0
Common stock class A, shares repurchased	23,156,433	20,900,264
Common stock class A, share repurchase price per share	$ 17.35
Remaining authorized amount	$ 79.5
Antidilutive stock options excluded in computation of diluted earnings per share	400,000	800,000	1,000,000
Common Class B [Member]
Capital Structure And Per Share Data [Line Items]
Common stock, shares authorized	30,000,000	30,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, number of votes per share	10