GAIN ON SALE OF ASSETS 2 (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loss (gain) on disposal
(Gain) loss on sale of assets	$ 0	$ (35,310)	$ 99,767
San Jose Corporate Headquarters [Member]
Loss (gain) on disposal
Sales price		(48,500)
Net assets transferred, including working capital		12,262
Transaction related costs		2,810
(Gain) loss on sale of assets		$ (33,428)	$ 0

The sale price associated from the sale of a portion of the Company's business, for example a segment, division, branch or other business, during the period.

No definition available.

+ Details

Name:	atml_DisposalGroupIncludingDiscontinuedOperationSalesPrice
Namespace Prefix:	atml_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the transaction costs as a part of the sale of assets.

+ References

No definition available.

+ Details

Name:	atml_DisposalGroupIncludingDiscontinuedOperationTransactionCost
Namespace Prefix:	atml_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

In a transaction not treated as a divestiture for accounting purposes and in which the disposed operation is not consolidated for accounting purposes, the aggregate amount of the disposed assets that are segregated in the balance sheet.

+ References

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section E

-Paragraph Question 2

+ Details

Name:	us-gaap_DisposalGroupAssetsOfBusinessTransferredUnderContractualArrangement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The gains (losses) included in earnings resulting from the sale or disposal of tangible assets. This item does not include any gain (loss) recognized on the sale of oil and gas property or timber property.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2941-110230

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

- Details

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