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Summary of Significant Accounting Policies (Details Textual) (USD $) | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Apr. 30, 2011 | Jun. 30, 2012 | Mar. 31, 2012 | Dec. 31, 2011 | Jun. 30, 2011 | Dec. 31, 2012 Pension_Plan Customer | Dec. 31, 2011 Customer | Dec. 31, 2010
Summary of Significant Accounting Policies (Textual) [Abstract] |  |  |  |  |  |  |  |
Carrying value of notes receivable and investment |  |  |  |  |  | $ 0 |  |
Proceeds from Sale of Equity Method Investment in NWPA | 800,000 |  |  |  |  |  |  |
Purchases of property and equipment from NWPA |  |  |  | 200,000 |  |  | 200,000 |
Intercompany balances |  |  |  | 0 |  |  | 0 |
Net sales recognized under percentage of completion accounting |  |  | 800,000 |  |  |  |  |
Cost of sales reduction |  | 200,000 | 100,000 | 100,000 |  | 400,000 |  |
Proceeds from sale of traffic systems assets |  |  |  |  | 13,700,000 |  |  |
Gain on sale of traffic systems assets |  |  |  |  | 2,900,000 |  |  |
Goodwill written off related to sale of traffic systems assets |  |  |  |  |  |  | 973,000 |
Restricted cash held in the escrow account |  |  |  | 900,000 |  | 900,000 | 900,000 |
Goodwill balance, Tubular Products Group |  |  |  | 20,478,000 |  | 20,478,000 | 20,478,000 | 21,451,000
Number of defined benefit pension plans |  |  |  |  |  | 2 |  |
Nonrecurring fair value measurement impairment charge |  |  |  |  |  | 0 | 4,100,000 |
Pension liability adjustment, tax effect |  |  |  |  |  | 1,244,000 | 1,294,000 |
Net deferred gain (loss) on cash flow derivatives, tax effect |  |  |  |  |  | 50,000 | 44,000 |
Number of customers with balances in excess of 10% of total accounts receivable |  |  |  |  |  | 0 | 1 |
Customer with receivable balance in excess of 10% (1) |  |  |  |  |  | 10.00% |  |
Customer with receivable balance in excess of 10% (2) |  |  |  |  |  |  | 13.00% |
Advanced deposits |  |  |  | 2,000,000 |  | 9,400,000 | 2,000,000 |
Accumulated impairment charges |  |  |  |  |  | $ 0 |  |
Minimum percentage of likelihood of tax benefit being realized upon settlement |  |  |  |  |  | 50.00% |  |

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