Acquisitions (Policies)	6 Months Ended
Acquisitions (Policies)	Jun. 30, 2012
Accounting Policies [Abstract]
Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy	Each reporting period, the Company adjusts the carrying amount of the noncontrolling interest to the greater of (1) the initial carrying amount, increased or decreased for the noncontrolling interest's share of Arminak's net income or loss and its share of comprehensive income or loss and dividends and (2) the redemption value as determined by the specified multiple of earnings, as defined. This method views the end of the reporting period as if it were also the redemption date for the redeemable noncontrolling interest. If the fair value of the redeemable noncontrolling interest is less than the redemption value, there may be a charge to earnings per share attributable to TriMas Corporation.

Disclosure of accounting policy for subsidiaries or other investments that are consolidated, including the accounting treatment for intercompany accounts or transactions and any noncontrolling interest.

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