Acquisitions (Details) (Acquired salvage vehicle and assets of an online marketing company [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
Jan. 31, 2015
Business Acquisition [Line Items]
Decrease in goodwill	$ 0.8us-gaap_GoodwillPeriodIncreaseDecrease
Increase in intangible assets	$ 0.9
Covenants not to compete \| Minimum
Business Acquisition [Line Items]
Useful life of intangible assets	3 years
Covenants not to compete \| Maximum
Business Acquisition [Line Items]
Useful life of intangible assets	8 years
Supply contracts \| Minimum
Business Acquisition [Line Items]
Useful life of intangible assets	3 years
Supply contracts \| Maximum
Business Acquisition [Line Items]
Useful life of intangible assets	8 years
Customer relationships \| Minimum
Business Acquisition [Line Items]
Useful life of intangible assets	3 years
Customer relationships \| Maximum
Business Acquisition [Line Items]
Useful life of intangible assets	8 years
Trade names \| Minimum
Business Acquisition [Line Items]
Useful life of intangible assets	3 years
Trade names \| Maximum
Business Acquisition [Line Items]
Useful life of intangible assets	8 years
Licenses and databases \| Minimum
Business Acquisition [Line Items]
Useful life of intangible assets	3 years
Licenses and databases \| Maximum
Business Acquisition [Line Items]
Useful life of intangible assets	8 years
Software \| Minimum
Business Acquisition [Line Items]
Useful life of intangible assets	3 years
Software \| Maximum
Business Acquisition [Line Items]
Useful life of intangible assets	8 years

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in intangible assets (for example patents and licenses).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

Name:	us-gaap_IncreaseDecreaseInIntangibleAssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration