XML 114 R100.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Narrative (Details) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2016 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2015 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) year | Dec. 31, 2014 USD ($)
Valuation Allowance [Line Items] |  |  |  |  |  |
Valuation allowance for deferred tax assets | $ 322.2 |  |  | $ 322.2 | $ 105.1 |
Number of Years in Cumulative Loss Profit Position | year |  |  |  |  | 3 |
Valuation allowance |  |  |  | 171.5 | $ 74.5 | $ 0.5
Deferred tax asset valuation allowance charge | 22.5 | $ (173.1) | $ (63.9) |  |  |
Valuation allowance applicable to other comprehensive income |  |  |  | 130.4 | 121.7 | 270.3
Income tax refunds received |  |  |  | 10.5 | 63.3 | 20.2
Operating loss carryforwards, Amount of income utilizable per year | $ 5.0 |  |  | $ 5.0 |  |
Operating loss carryforwards, Amount of income utilizable per year percent | 30.00% |  |  | 30.00% |  |
Federal and State Deferred Tax Assets [Member] |  |  |  |  |  |
Valuation Allowance [Line Items] |  |  |  |  |  |
Deferred tax asset valuation allowance charge |  |  |  | $ 165.8 | 68.4 |
State Tax Credits [Member] |  |  |  |  |  |
Valuation Allowance [Line Items] |  |  |  |  |  |
Valuation allowance for deferred tax assets | $ 13.3 |  |  | 13.3 | 13.8 |
State Temporary Differences [Member] |  |  |  |  |  |
Valuation Allowance [Line Items] |  |  |  |  |  |
Valuation allowance for deferred tax assets | 6.5 |  |  | 6.5 | 3.3 |
Accumulated Deferred Tax Asset Valuation Allowance [Member] |  |  |  |  |  |
Valuation Allowance [Line Items] |  |  |  |  |  |
Valuation allowance applicable to other comprehensive income |  |  |  | 45.6 | 0.0 | $ 0.0
Federal [Member] |  |  |  |  |  |
Valuation Allowance [Line Items] |  |  |  |  |  |
Income tax refunds received |  |  |  | 7.3 | $ 59.9 |
Net operating loss carryforwards | 323.0 |  |  | 323.0 |  |
Tax credit carryforwards | 52.0 |  |  | 52.0 |  |
State [Member] |  |  |  |  |  |
Valuation Allowance [Line Items] |  |  |  |  |  |
Net operating loss carryforwards | 83.0 |  |  | 83.0 |  |
Tax credit carryforwards | $ 13.0 |  |  | $ 13.0 |  |

X
- Definition Number of Years in Cumulative Loss/Profit Position + References No definition available. + Details
Name: | ati_NumberofYearsinCumulativeLossProfitPosition
Namespace Prefix: | ati_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Operating Loss Carryforwards, Amount of Income Utilizable Per Year + References No definition available. + Details
Name: | ati_OperatingLossCarryforwardsAmountofIncomeUtilizablePerYear
Namespace Prefix: | ati_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Operating Loss Carryforwards, Amount of Income Utilizable Per Year, Percentage + References No definition available. + Details
Name: | ati_OperatingLossCarryforwardsAmountofIncomeUtilizablePerYearPercentage
Namespace Prefix: | ati_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e32123-109318 + Details
Name: | us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32559-109319 + Details
Name: | us-gaap_OperatingLossCarryforwards
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=66004921&loc=d3e1436-108581 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669686-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of cash received during the period as refunds for the overpayment of taxes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586 + Details
Name: | us-gaap_ProceedsFromIncomeTaxRefunds
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32559-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Carryforwards -URI http://asc.fasb.org/extlink&oid=6506874 + Details
Name: | us-gaap_TaxCreditCarryforwardAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e32123-109318 + Details
Name: | us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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. + References No definition available. + Details
Name: | us-gaap_ValuationAllowanceLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ValuationAllowanceByDeferredTaxAssetAxis=ati_FederalandStateDeferredTaxAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationAllowanceByDeferredTaxAssetAxis=ati_StateTaxCreditsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationAllowanceByDeferredTaxAssetAxis=ati_StateTemporaryDifferencesMember
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: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |