Annual report pursuant to Section 13 and 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 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Segment Reporting Information [Line Items]                        
Total consolidated revenues $ 2,351,828us-gaap_Revenues $ 2,355,604us-gaap_Revenues $ 2,353,280us-gaap_Revenues $ 2,136,387us-gaap_Revenues $ 2,315,369us-gaap_Revenues $ 2,242,197us-gaap_Revenues $ 2,202,436us-gaap_Revenues $ 2,083,166us-gaap_Revenues $ 9,197,099us-gaap_Revenues $ 8,843,168us-gaap_Revenues $ 8,365,468us-gaap_Revenues  
Total segment income                 214,820sah_SegmentReportingIncomeLoss 212,649sah_SegmentReportingIncomeLoss 220,948sah_SegmentReportingIncomeLoss  
Interest expense, other, net                 (53,190)us-gaap_InterestExpenseOther (55,485)us-gaap_InterestExpenseOther (60,090)us-gaap_InterestExpenseOther  
Other income (expense), net                 97us-gaap_OtherNonoperatingIncomeExpense (28,143)us-gaap_OtherNonoperatingIncomeExpense (19,625)us-gaap_OtherNonoperatingIncomeExpense  
Income (loss) from continuing operations before taxes                 161,727us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments 129,021us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments 141,233us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments  
Total floorplan interest expense                 18,793sah_FloorPlanInterestExpense 21,954sah_FloorPlanInterestExpense 19,454sah_FloorPlanInterestExpense  
Total depreciation and amortization                 58,260us-gaap_DepreciationAndAmortization 54,007us-gaap_DepreciationAndAmortization 45,285us-gaap_DepreciationAndAmortization  
Total capital expenditures                 146,432us-gaap_PaymentsToAcquirePropertyPlantAndEquipment 157,617us-gaap_PaymentsToAcquirePropertyPlantAndEquipment 95,376us-gaap_PaymentsToAcquirePropertyPlantAndEquipment  
Total assets 3,183,135us-gaap_Assets       3,051,170us-gaap_Assets       3,183,135us-gaap_Assets 3,051,170us-gaap_Assets    
Cash and cash equivalents 4,182us-gaap_CashAndCashEquivalentsAtCarryingValue       3,016us-gaap_CashAndCashEquivalentsAtCarryingValue       4,182us-gaap_CashAndCashEquivalentsAtCarryingValue 3,016us-gaap_CashAndCashEquivalentsAtCarryingValue 3,371us-gaap_CashAndCashEquivalentsAtCarryingValue 1,913us-gaap_CashAndCashEquivalentsAtCarryingValue
Goodwill, Net 475,929us-gaap_Goodwill       476,315us-gaap_Goodwill       475,929us-gaap_Goodwill 476,315us-gaap_Goodwill 454,224us-gaap_Goodwill  
Other Intangible Assets, net 83,720us-gaap_IntangibleAssetsNetExcludingGoodwill       87,866us-gaap_IntangibleAssetsNetExcludingGoodwill       83,720us-gaap_IntangibleAssetsNetExcludingGoodwill 87,866us-gaap_IntangibleAssetsNetExcludingGoodwill    
Other Corporate and other assets 735,227us-gaap_OtherAssets       600,870us-gaap_OtherAssets       735,227us-gaap_OtherAssets 600,870us-gaap_OtherAssets    
Franchised Dealerships [Member]                        
Segment Reporting Information [Line Items]                        
Total consolidated revenues                 9,191,661us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
8,843,168us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
8,365,468us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
 
Total segment income                 230,733sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
218,139sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
221,721sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
 
Total floorplan interest expense                 18,727sah_FloorPlanInterestExpense
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
21,954sah_FloorPlanInterestExpense
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
19,454sah_FloorPlanInterestExpense
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
 
Total depreciation and amortization                 58,001us-gaap_DepreciationAndAmortization
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
54,007us-gaap_DepreciationAndAmortization
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
45,285us-gaap_DepreciationAndAmortization
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
 
Total capital expenditures                 117,129us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
151,947us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
95,376us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
 
Total assets 1,841,962us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
      1,877,433us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
      1,841,962us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
1,877,433us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_FranchisedDealershipsMember
   
Echo Park [Member]                        
Segment Reporting Information [Line Items]                        
Total consolidated revenues                 5,438us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
     
Total segment income                 (15,913)sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
(5,490)sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
(773)sah_SegmentReportingIncomeLoss
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
 
Total floorplan interest expense                 66sah_FloorPlanInterestExpense
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
     
Total depreciation and amortization                 259us-gaap_DepreciationAndAmortization
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
     
Total capital expenditures                 29,303us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
5,670us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
   
Total assets $ 42,115us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
      $ 5,670us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
      $ 42,115us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember
$ 5,670us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= sah_EchoParkMember