XML 77 R67.htm IDEA: XBRL DOCUMENT
v3.24.2.u1

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2024 | Jul. 02, 2023 | Jun. 30, 2024 | Jul. 02, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance | $ (88.8) | $ (87.6) | $ (83.2) | $ (67.4)
OCI before reclassifications | (3.5) | (4.3) | (11.3) | (16.8)
Amounts reclassified from AOCI | 2.1 | 4.6 | 4.3 | (3.1)
Net current-period OCI | (1.4) | 0.3 | (7.0) | (19.9)
Ending balance | (90.2) | (87.3) | (90.2) | (87.3)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] |  |  |  |
Beginning balance | 7.1 | 12.1 | 7.3 | 7.7
OCI before reclassifications | (0.6) | (5.7) | (0.8) | (1.3)
Amounts reclassified from AOCI | 0.0 | 0.0 | 0.0 | 0.0
Net current-period OCI | (0.6) | (5.7) | (0.8) | (1.3)
Ending balance | 6.5 | 6.4 | 6.5 | 6.4
Post- retirement benefit plans [Member] |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance | (31.6) | (33.6) | (32.5) | (34.7)
OCI before reclassifications | 0.0 | 0.0 | 0.0 | 0.0
Amounts reclassified from AOCI | 0.9 | 1.0 | 1.8 | 2.1
Net current-period OCI | 0.9 | 1.0 | 1.8 | 2.1
Ending balance | (30.7) | (32.6) | (30.7) | (32.6)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] |  |  |  |
Beginning balance | 0.0 | 0.0 | 0.0 | 0.0
OCI before reclassifications | 0.0 | 0.0 | 0.0 | 0.0
Amounts reclassified from AOCI | 0.0 | 0.0 | 0.0 | 0.0
Net current-period OCI | 0.0 | 0.0 | 0.0 | 0.0
Ending balance | 0.0 | 0.0 | 0.0 | 0.0
Currency translation adjustment [Member] |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance | (74.8) | (71.2) | (68.4) | (70.1)
OCI before reclassifications | (3.1) | (2.4) | (9.5) | (3.5)
Amounts reclassified from AOCI | 0.0 | 0.0 | 0.0 | 0.0
Net current-period OCI | (3.1) | (2.4) | (9.5) | (3.5)
Ending balance | (77.9) | (73.6) | (77.9) | (73.6)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] |  |  |  |
Beginning balance | 7.1 | 12.1 | 7.3 | 7.7
OCI before reclassifications | (0.6) | (5.7) | (0.8) | (1.3)
Amounts reclassified from AOCI | 0.0 | 0.0 | 0.0 | 0.0
Net current-period OCI | (0.6) | (5.7) | (0.8) | (1.3)
Ending balance | 6.5 | 6.4 | 6.5 | 6.4
Derivatives [Member] |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance | (6.5) | (2.1) | (6.4) | 13.5
OCI before reclassifications | (0.4) | (1.9) | (1.8) | (13.3)
Amounts reclassified from AOCI | 2.0 | 2.9 | 3.3 | (1.3)
Net current-period OCI | 1.6 | 1.0 | 1.5 | (14.6)
Ending balance | (4.9) | (1.1) | (4.9) | (1.1)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] |  |  |  |
Beginning balance | 0.0 | 0.0 | 0.0 | 0.0
OCI before reclassifications | 0.0 | 0.0 | 0.0 | 0.0
Amounts reclassified from AOCI | 0.0 | 0.0 | 0.0 | 0.0
Net current-period OCI | 0.0 | 0.0 | 0.0 | 0.0
Ending balance | 0.0 | 0.0 | 0.0 | 0.0
Accumulated Deferred Tax Asset Valuation Allowance [Member] |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |
Beginning balance | 24.1 | 19.3 | 24.1 | 23.9
OCI before reclassifications | 0.0 | 0.0 | 0.0 | 0.0
Amounts reclassified from AOCI | (0.8) | 0.7 | (0.8) | (3.9)
Net current-period OCI | (0.8) | 0.7 | (0.8) | (3.9)
Ending balance | 23.3 | 20.0 | 23.3 | 20.0
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] |  |  |  |
Beginning balance | 0.0 | 0.0 | 0.0 | 0.0
OCI before reclassifications | 0.0 | 0.0 | 0.0 | 0.0
Amounts reclassified from AOCI | 0.0 | 0.0 | 0.0 | 0.0
Net current-period OCI | 0.0 | 0.0 | 0.0 | 0.0
Ending balance | $ 0.0 | $ 0.0 | $ 0.0 | $ 0.0

X
- Definition Accumulated Other Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest + References No definition available. + Details
Name: | ati_AccumulatedOtherComprehensiveIncomeLossNetofTaxAttributabletoNoncontrollingInterest
Namespace Prefix: | ati_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] + References No definition available. + Details
Name: | ati_IncreaseDecreaseinStockholdersEquityAttributabletoNoncontrollingInterestRollForward
Namespace Prefix: | ati_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Other Comprehensive Income Loss Before Reclassification Adjustments Net Of Tax Attributable To Noncontrolling Interest + References No definition available. + Details
Name: | ati_OtherComprehensiveIncomeLossBeforeReclassificationAdjustmentsNetOfTaxAttributableToNoncontrollingInterest
Namespace Prefix: | ati_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Other Comprehensive Income (Loss), before Reclassifications, Net of Tax, Attributable to Noncontrolling Interest + References No definition available. + Details
Name: | ati_OtherComprehensiveIncomeLossbeforeReclassificationsNetofTaxAttributabletoNoncontrollingInterest
Namespace Prefix: | ati_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax, Attributable to Noncontrolling Interest + References No definition available. + Details
Name: | ati_ReclassificationfromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetofTaxAttributabletoNoncontrollingInterest
Namespace Prefix: | ati_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Reclassification from Accumulated Other Comprehensive Income (Loss), Current Period, Net of Tax, Attributable to Noncontrolling Interest + References No definition available. + Details
Name: | ati_ReclassificationfromAccumulatedOtherComprehensiveIncomeLossCurrentPeriodNetofTaxAttributabletoNoncontrollingInterest
Namespace Prefix: | ati_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-11 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 65 -Paragraph 2 -Subparagraph (g)(2)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480016/944-40-65-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 65 -Paragraph 2 -Subparagraph (h)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480016/944-40-65-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(23)(a)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14 + Details
Name: | us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_IncreaseDecreaseInStockholdersEquityRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482765/220-10-50-5 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481674/830-30-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481694/830-30-45-17 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 20 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481694/830-30-45-20 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(19)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482765/220-10-50-4 Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 15 -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482739/220-10-55-15 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax of other comprehensive income (loss) attributable to noncontrolling interests. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 810 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 19 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-19 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 20 -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-20 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (c)(3) -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481203/810-10-50-1A Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 250 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483443/250-10-50-6 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after tax of other comprehensive income (loss) attributable to parent entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 810 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 19 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-19 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 20 -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-20 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (c)(3) -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481203/810-10-50-1A Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 250 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483443/250-10-50-6 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482765/220-10-50-5 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481674/830-30-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481694/830-30-45-17 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 20 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481694/830-30-45-20 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(19)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482765/220-10-50-4 Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 15 -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482739/220-10-55-15 + Details
Name: | us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedTranslationAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=ati_AccumulatedDeferredTaxAssetValuationAllowanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |