Business Acquisition, Anticipated Period for Completion of Purchase

No definition available.

Name:	alg_BusinessAcquisitionAnticipatedPeriodforCompletionofPurchase
Namespace Prefix:	alg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Disposal Group, Including Discontinued Operation, Consideration

+ References

No definition available.

+ Details

Name:	alg_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix:	alg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Total revenue reported by the acquired entity for its previous full fiscal year before the business acquisition.

+ References

No definition available.

+ Details

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

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7488404&loc=d3e6927-128479

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The number of businesses acquired by the entity during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfBusinessesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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

Subsequent Events (Details) (Subsequent Event, USD $)				0 Months Ended
Subsequent Events (Details) (Subsequent Event, USD $)	Feb. 24, 2014	Dec. 31, 2013	Mar. 11, 2014 SMC Plant	Feb. 24, 2014 Super Products LLC, Wausau-Everest LP, and Howard P Fairfield LLC Operation
Subsequent Event [Line Items]
Number of operations acquired				3
Net sales of acquired operations during 2013				$ 139,000,000
Total consideration transferred				186,000,000
Anticipated period for completion of purchase				45 days
Line of credit	250,000,000	100,000,000
Sales price for SMC plant			$ 900,000