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v2.4.1.9

Goodwill and Related Intangible Assets (Schedule of Goodwill Impairment Tests) (Details) | Oct. 31, 2014 | Oct. 31, 2013
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Minimum |  |
Goodwill [Line Items] |  |
WACC | 12.90%rock_WeightedAverageCostOfCapital / us-gaap_RangeAxis = us-gaap_MinimumMember | 11.10%rock_WeightedAverageCostOfCapital / us-gaap_RangeAxis = us-gaap_MinimumMember
Maximum |  |
Goodwill [Line Items] |  |
WACC | 13.60%rock_WeightedAverageCostOfCapital / us-gaap_RangeAxis = us-gaap_MaximumMember | 12.70%rock_WeightedAverageCostOfCapital / us-gaap_RangeAxis = us-gaap_MaximumMember

X
- Definition Weighted Average Cost Of Capital + References No definition available. + Details
Name: | rock_WeightedAverageCostOfCapital
Namespace Prefix: | rock_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |