SALE OF ASSETS (Narrative) (Details) - USD ($) $ in Thousands			6 Months Ended	12 Months Ended
	Sep. 23, 2015	Sep. 28, 2012	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 16, 2015	Mar. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Consideration	$ 11,500						$ 16,700
Sale Leaseback Transaction, Lease Terms	P3Y
Gain (Loss) on Disposition of Assets	$ 3,100
atml_Othercomprehensivelossrelatedtodiscontinuationofequityinvestment	2,100
Sale Leaseback Transaction, Deferred Gain, Net	$ 1,100
(Gains) losses on sale of assets, net				$ 1,626	$ 4,364	$ 886
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			$ 200
North Tyneside [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Gains) losses on sale of assets, net					4,400
Fee associated with disposal of property plant and equipment				500
Interest Income, Other				$ 1,300
Equity Method Investment, Ownership Percentage				50.20%
Disposal of Product Line Sale Proceeds		$ 25,000
Assets of Disposal Group, Including Discontinued Operation, Current								$ 7,000
Deferred Gain on Sale of Property					$ 4,400