Quarterly report pursuant to Section 13 or 15(d)

Segment Information - Summary of Reportable Operating Segment (Detail)

v2.4.1.9
Segment Information - Summary of Reportable Operating Segment (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Segment Reporting Information [Line Items]    
Total consolidated revenues $ 2,235,515us-gaap_Revenues $ 2,136,386us-gaap_Revenues
Total segment income 36,718sah_SegmentReportingIncomeLoss 45,954sah_SegmentReportingIncomeLoss
Interest expense, other, net (13,219)us-gaap_InterestExpenseOther (13,818)us-gaap_InterestExpenseOther
Other income (expense), net 90us-gaap_OtherNonoperatingIncomeExpense 97us-gaap_OtherNonoperatingIncomeExpense
Income (loss) from continuing operations before taxes 23,589us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments 32,233us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Franchised Dealerships [Member]    
Segment Reporting Information [Line Items]    
Total consolidated revenues 2,219,830us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
2,136,386us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
Total segment income 43,072sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
47,696sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
Echo Park [Member]    
Segment Reporting Information [Line Items]    
Total consolidated revenues 15,685us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
 
Total segment income $ (6,354)sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
$ (1,742)sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember