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Operating Segments and Concentrations of Credit Risk (Major Customers) (Details)
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Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2009
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|---|---|---|---|
| Percentage of the consolidated revenues | 74.00% | 73.00% | 74.00% |
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AT&T [Member]
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| Percentage of the consolidated revenues | 23.00% | 21.00% | 20.00% |
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Sprint [Member]
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| Percentage of the consolidated revenues | 21.00% | 20.00% | 22.00% |
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Verizon Wireless [Member]
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| Percentage of the consolidated revenues | 19.00% | 21.00% | 19.00% |
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T-Mobile [Member]
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| Percentage of the consolidated revenues | 11.00% | 11.00% | 13.00% |