Commitments and Contingencies Metaldyne Corporation (Details) (USD $)	3 Months Ended
Mar. 31, 2007	Dec. 31, 2014
Loss Contingencies [Line Items]
Common Stock Dividends, Shares	4,825,587us-gaap_CommonStockDividendsShares
Loss Contingency, Estimate of Possible Loss		$ 6,700,000
Loss Contingency, Range of Possible Loss, Maximum		9,100,000
Loss Contingency, Range of Possible Loss, Portion Not Accrued		2,400,000
Allocated Share of Liabilities Not Readily Associated with the Business - TriMas		42.01%
Allocated Share of Liabilities Not Readily Associated with the Business - Metaldyne		57.99%
Indemnification Deductible		$ 50,000trs_IndemnificationDeductible

Allocated Share of Liabilities Not Readily Associated with the Business - Metaldyne

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Allocated Share of Liabilities Not Readily Associated with the Business

+ References

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Indemnification Deductible

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- Definition

Number of shares of common stock issued as dividends during the period. Excludes stock splits.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

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-Section 50

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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

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The estimated maximum amount of possible loss from the contingency.

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The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date.

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-Name Accounting Standards Codification

-Topic 450

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