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Long-Term Debt - Summary of Interest Received and Paid under Term of Cash Flow Swap (Detail) (USD $)
In Millions, unless otherwise specified
|
3 Months Ended |
|
Mar. 31, 2015
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| Derivatives, Fair Value [Line Items] |
|
| Receive Rate |
One-month LIBOR
|
| Variable Interest Rate |
0.179%us-gaap_DerivativeVariableInterestRate
|
| Cash Flow Swap [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
2.7us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapMember
|
| Pay Rate |
7.10%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapMember
|
| Receive Rate |
one-month LIBOR + 1.50%
|
| Maturing Date |
Jul. 10, 2017
|
| Variable Interest Rate |
1.50%us-gaap_DerivativeVariableInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapMember
|
| Cash Flow Swap 1 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
8.5us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapOneMember
|
| Pay Rate |
4.655%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapOneMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Dec. 10, 2017
|
| Cash Flow Swap 2 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
7.3us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTwoMember
|
| Pay Rate |
6.86%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTwoMember
|
| Receive Rate |
one-month LIBOR + 1.25%
|
| Maturing Date |
Aug. 01, 2017
|
| Variable Interest Rate |
1.25%us-gaap_DerivativeVariableInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTwoMember
|
| Cash Flow Swap 3 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
100.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapThreeMember
|
| Pay Rate |
3.28%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapThreeMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2015
|
| Cash Flow Swap 4 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
100.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFourMember
|
| Pay Rate |
3.30%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFourMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2015
|
| Cash Flow Swap 5 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
6.3us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFiveMember
|
| Pay Rate |
6.41%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFiveMember
|
| Receive Rate |
one-month LIBOR + 1.25%
|
| Maturing Date |
Aug. 12, 2017
|
| Variable Interest Rate |
1.25%us-gaap_DerivativeVariableInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFiveMember
|
| Cash Flow Swap 6 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
50.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapSixMember
|
| Pay Rate |
3.24%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapSixMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2017
|
| Cash Flow Swap 7 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
50.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapSevenMember
|
| Pay Rate |
3.07%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapSevenMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2017
|
| Cash Flow Swap 8 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
100.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapEightMember
|
| Pay Rate |
2.065%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapEightMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jun. 30, 2017
|
| Cash Flow Swap 9 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
100.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapNineMember
|
| Pay Rate |
2.015%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapNineMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jun. 30, 2017
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| Cash Flow Swap 10 [Member] |
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| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
200.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTenMember
|
| Pay Rate |
0.788%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTenMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2016
|
| Cash Flow Swap 11 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
50.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapElevenMember
|
| Pay Rate |
1.32%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapElevenMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2017
|
| Cash Flow Swap 12 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
250.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTwelveMember
|
| Pay Rate |
1.887%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapTwelveMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jun. 30, 2018
|
| Cash Flow Swap 13 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
25.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapThirteenMember
|
| Pay Rate |
2.08%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapThirteenMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2017
|
| Cash Flow Swap 14 [Member] |
|
| Derivatives, Fair Value [Line Items] |
|
| Notional Amount |
100.0us-gaap_DerivativeLiabilityNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFourteenMember
|
| Pay Rate |
1.56%us-gaap_DerivativeFixedInterestRate
/ us-gaap_DerivativeInstrumentRiskAxis
= sah_CashFlowSwapFourteenMember
|
| Receive Rate |
one-month LIBOR
|
| Maturing Date |
Jul. 01, 2017
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