XML 34 R31.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Summary of Significant Accounting Policies - Summary of Operating Lease Exit Accruals (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2014
Accounting Policies [Abstract] |
Component of lease exit expense in interest expense, other, net | $ 0.1
Component of lease exit expense in income (loss) from operations and the sale of dealerships | 0.3
Component of lease exit payments in selling, general and administrative expenses | 0.2
Component of lease exit payments in income (loss) from operations and the sale of dealerships | $ 1.8

X
- Definition Lease exit expense discontinued operations. + References No definition available. + Details
Name: | sah_LeaseExitExpenseDiscontinuedOperations
Namespace Prefix: | sah_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Lease exit expense interest other. + References No definition available. + Details
Name: | sah_LeaseExitExpenseInterestOther
Namespace Prefix: | sah_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Lease exit payment discontinued operations. + References No definition available. + Details
Name: | sah_LeaseExitPaymentDiscontinuedOperations
Namespace Prefix: | sah_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Lease exit payment selling general and administrative. + References No definition available. + Details
Name: | sah_LeaseExitPaymentSellingGeneralAndAdministrative
Namespace Prefix: | sah_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration