(GAIN) LOSS ON SALE OF ASSETS AND ASSET IMPAIRMENT CHARGES (Details 3) (INSIDE, USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Jun. 30, 2010	Sep. 30, 2011
INSIDE
Variable interest entity
Period of commitments to purchase wafers from LFoundry (in years)	3Y
Cost of investment		$ 3,936
Percentage of ownership		3.00%

Represents the period of the unconditional purchase obligation that is not recorded as a liability on the balance sheet.

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Namespace Prefix:	atml
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the aggregate cost of investments in variable interest entity.

+ Details

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Namespace Prefix:	atml
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_VariableInterestEntityLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 5A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6970148&loc=SL6759159-111685

+ Details

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Balance Type:	na
Period Type:	duration