Name:	ati_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToIndividualForeignCountriesPercentageAmount
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Data Type:	num:percentItemType
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-- None. No documentation exists for this element. --

No definition available.

Name:	ati_EntityWideDisclosureOnGeographicAreasTotalAssetsAttributedToIndividualCountriesPercentageAmount
Namespace Prefix:	ati_
Data Type:	num:percentItemType
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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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 210.5-02.18)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 12
-Article 7

Name:	us-gaap_Assets
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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.

No definition available.

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

Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(a))
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueGoodsNet
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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Name:	us-gaap_StatementGeographicalAxis=country_LU
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Name:	us-gaap_StatementGeographicalAxis=country_DE
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