| Component: (Network and Table) | |
|---|---|
| Network | 2412405 - Disclosure - Retirement Benefits (Details 3) (http://www.atimetals.com/role/RetirementBenefitsDetails3) |
| Table | Schedule Of Defined Benefit Plans Disclosures [Table] |
| Reporting Entity [Axis] | 0001018963 (http://www.sec.gov/CIK) |
| Defined Benefit Plan Disclosure [Line Items] | Period [Axis] | |||||
|---|---|---|---|---|---|---|
2016-12-31 | 2015-12-31 | |||||
| Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] | Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] | |||||
| Pension Benefits [Member] | Other Postretirement Benefits [Member] | Pension Benefits [Member] | Other Postretirement Benefits [Member] | |||
| Range [Axis] | Range [Axis] | Range [Axis] | Range [Axis] | |||
| Range [Domain] | Range [Domain] | Minimum [Member] | Maximum [Member] | Range [Domain] | Range [Domain] | |
Discount rate | ||||||
Rate of increase in future compensation levels | ||||||