Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Fair Value and Carrying Value of Fixed Rate Long-Term Debt (Parenthetical) (Detail)

v2.4.1.9
Fair Value Measurements - Fair Value and Carrying Value of Fixed Rate Long-Term Debt (Parenthetical) (Detail)
Dec. 31, 2014
Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Stated interest rate on debt agreement 5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage  
7.0% Senior Subordinated Notes Due 2022 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Stated interest rate on debt agreement 7.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= sah_SevenPercentSeniorSubordinateNoteDueTwoThousandTwentyTwoMember 		7.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= sah_SevenPercentSeniorSubordinateNoteDueTwoThousandTwentyTwoMember
5.0% Senior Subordinated Notes due 2023 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Stated interest rate on debt agreement 5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= sah_FivePercentSeniorSubordinateNoteDueTwoThousandTwentyThreeMember 		5.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= sah_FivePercentSeniorSubordinateNoteDueTwoThousandTwentyThreeMember