Inventories (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Inventories
Retail automotive new vehicles	$ 1,814.3pag_AutomotiveInventoryNewVehiclesNet	$ 1,792.5pag_AutomotiveInventoryNewVehiclesNet
Retail automotive used vehicles	670.2pag_AutomotiveInventoryUsedVehiclesNet	639.9pag_AutomotiveInventoryUsedVehiclesNet
Retail automotive parts, accessories and other	101.7	103.5
Commercial truck dealership vehicles and parts	119.5	85.5
Commercial vehicle distribution vehicles and parts	180.0	197.8
Total inventories	$ 2,885.7us-gaap_InventoryNet	$ 2,819.2us-gaap_InventoryNet

Represents the carrying amount of commercial distribution vehicle inventory, net of valuation reserves.

No definition available.

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- Definition

Represents the carrying amount of commercial vehicle inventory, net of valuation reserves.

+ References

No definition available.

+ Details

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- Definition

Carrying amount of new vehicle inventory, net of valuation reserves.

+ References

No definition available.

+ Details

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- Definition

Carrying amount of parts, accessories and other inventory, net of valuation reserves.

+ References

No definition available.

+ Details

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- Definition

Carrying amount of used vehicle inventory, net of valuation reserves.

+ References

No definition available.

+ Details

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- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

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