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Commitments and Contingencies - Multiemployer Pension Plans (Details Textual 5)
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3 Months Ended |
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Mar. 31, 2013
PensionPlan
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| Commitments and Contingencies Disclosure [Abstract] | |
| Number of multi-employer pension plans (in number of plans) | 27 |
| Current employee participants in multi-employer plans | 20.00% |