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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) | 3 Months Ended | 12 Months Ended | 0 Months Ended | 12 Months Ended |  | 12 Months Ended |  | 12 Months Ended
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Jun. 30, 2011 | Dec. 31, 2013 Customer Segment Pension_Plan | Dec. 31, 2012 Customer | Dec. 30, 2013 Permalok Corporation [Member] | Dec. 31, 2013 Permalok Corporation [Member] | Dec. 31, 2013 Minimum [Member] | Dec. 31, 2013 Minimum [Member] Permalok Corporation [Member] | Dec. 31, 2013 Minimum [Member] Land Improvements [Member] | Dec. 31, 2013 Minimum [Member] Buildings [Member] | Dec. 31, 2013 Minimum [Member] Machinery and Equipment [Member] | Dec. 31, 2013 Maximum [Member] | Dec. 31, 2013 Maximum [Member] Permalok Corporation [Member] | Dec. 31, 2013 Maximum [Member] Land Improvements [Member] | Dec. 31, 2013 Maximum [Member] Buildings [Member] | Dec. 31, 2013 Maximum [Member] Machinery and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of reportable segments |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of investment |  | $ 0 | $ 0 |  |  |  |  |  |  |  |  |  |  |  |
Business acquisition date |  |  |  |  | Dec. 30, 2013 |  |  |  |  |  |  |  |  |  |
Business acquisition, percentage |  |  |  | 100.00% |  |  |  |  |  |  |  |  |  |  |
Business acquisition (net of received), amount paid |  | 15,689,000 |  |  | 15,700,000 |  |  |  |  |  |  |  |  |  |
Business acquisition, goodwill |  | 5,282,000 |  | 5,300,000 |  |  |  |  |  |  |  |  |  |  |
Business acquisition, contingent consideration recorded |  |  |  |  | 4,400,000 |  | 300,000 |  |  |  |  | 5,200,000 |  |  |
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 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Advanced deposits |  | $ 0 | $ 9,400,000 |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives of property and equipment |  |  |  |  |  |  |  | 15 years | 20 years | 3 years |  |  | 30 years | 40 years | 30 years
Estimated useful lives of intangible assets |  | 9 years 7 months 6 days |  |  |  | 3 years |  |  |  |  | 15 years |  |  |  |
Number of defined benefit pension plans |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |
Change in gross profit which triggers senior management review |  | 2.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum likelihood of tax benefit being realized in order for tax benefit to be recorded |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Number of customers with balances in excess of 10% of total accounts receivable |  | 2 | 0 |  |  |  |  |  |  |  |  |  |  |  |

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