|
Summary of Significant Accounting Policies - Additional Information (Detail)
|
3 Months Ended | |
|---|---|---|
|
Mar. 31, 2015
|
Mar. 31, 2014
|
|
| Significant Accounting Policies [Line Items] | ||
| Percentage of dealership that is accounted for under the equity method | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage | |
| Effective tax rate from continuing operations | 39.00%us-gaap_EffectiveIncomeTaxRateContinuingOperations | 38.00%us-gaap_EffectiveIncomeTaxRateContinuingOperations |
| Minimum [Member] | ||
| Significant Accounting Policies [Line Items] | ||
| Expected effective tax rate for continuing operations Range |
38.00%sah_EffectiveIncomeTaxRateContinuingOperationsFuturePeriod / us-gaap_RangeAxis = us-gaap_MinimumMember |
|
| Maximum [Member] | ||
| Significant Accounting Policies [Line Items] | ||
| Expected effective tax rate for continuing operations Range |
40.00%sah_EffectiveIncomeTaxRateContinuingOperationsFuturePeriod / us-gaap_RangeAxis = us-gaap_MaximumMember |
|
| X | ||||||||||
|
- Definition
Effective income tax rate continuing operations future period . No definition available.
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Details
|