Annual report pursuant to Section 13 and 15(d)

Capital Structure and Per Share Data - Dilutive Effect on Earnings Per Share (Parenthetical) (Detail)

v2.4.1.9
Capital Structure and Per Share Data - Dilutive Effect on Earnings Per Share (Parenthetical) (Detail)
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Schedule Of Earnings Per Share [Line Items]      
Stated interest rate on debt agreement 5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage    
5.0% Convertible Senior Notes [Member]      
Schedule Of Earnings Per Share [Line Items]      
Stated interest rate on debt agreement 5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= sah_FivePointZeroPercentConvertibleSeniorNotesDueTwoThousandTwentyNineMember 		5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= sah_FivePointZeroPercentConvertibleSeniorNotesDueTwoThousandTwentyNineMember 		5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= sah_FivePointZeroPercentConvertibleSeniorNotesDueTwoThousandTwentyNineMember