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Summary of Significant Accounting Policies - Additional Information (Details) |  | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Apr. 01, 2020 company | Jun. 30, 2018 USD ($) | Dec. 31, 2020 USD ($) reporting_unit segment | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Mar. 31, 2020 | Mar. 30, 2020
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Number of independent, publicly-traded companies resulting from proposed separation transaction | company | 2 |  |  |  |  |  |
Number of new segments | segment |  |  | 4 |  |  |  |
Capital expenditures |  |  | $ 267,000,000 | $ 641,000,000 | $ 768,000,000 |  |
Retained earnings (A) |  |  | $ 364,000,000 | 113,000,000 |  |  |
Number of reporting units | reporting_unit |  |  | 4 |  |  |  |
Minimum percentage of estimated fair value of reporting unit to be less than carrying amount of goodwill |  |  | 50.00% |  |  |  |
Period required for impairment testing of reporting units |  |  | 3 years |  |  |  |
Percentage of fair value in excess of carrying amount |  |  | 50.00% |  |  |  |
Impairment of goodwill (A and N) |  |  | $ 0 | 2,000,000 |  |  |
Advance payment |  |  | $ 85,000,000 | 97,000,000 |  |  |
Businesses expected to be disposed within, years |  |  | 1 year |  |  |  |
Revision of Prior Period, Error Correction, Adjustment |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Capital expenditures |  |  |  | $ 55,000,000 |  |  |
Retained earnings (A) |  |  |  |  | $ 16,000,000 |  |
Aerospace | Revenue Benchmark | Customer Concentration Risk |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Concentration risk, percentage |  |  | 69.00% | 71.00% | 70.00% |  |
Disks Asset Group |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Impairment of goodwill (A and N) |  | $ 0 |  |  |  |  |
Engineered Structures |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Percentage of fair value in excess of carrying amount |  |  |  |  |  | 15.00% | 60.00%

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