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Segment Reporting (Revenue by Geographical Areas) (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2016 | Mar. 31, 2015
Revenues from External Customers [Line Items] |  |
Revenues | $ 582,040 | $ 430,045
Revenue as Percentage of Consolidated Revenue | 100.00% | 100.00%
Domestic [Member] |  |
Revenues from External Customers [Line Items] |  |
Revenues | $ 554,438 | $ 410,756
Revenue as Percentage of Consolidated Revenue | 95.30% | 95.50%
Foreign [Member] |  |
Revenues from External Customers [Line Items] |  |
Revenues | $ 27,602 | $ 19,289
Revenue as Percentage of Consolidated Revenue | 4.70% | 4.50%

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