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International Risk Factors (Details) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2016 USD ($) | Mar. 31, 2015 USD ($) | Mar. 31, 2016 USD ($) item | Mar. 31, 2015 USD ($) | Jun. 30, 2010 item
Number of rigs expropriated by Venezuelan government |  |  |  |  | 11
Foreign currency gains losses | $ | $ (0.2) | $ 0.3 | $ 8.3 | $ 1.7 |
Operating revenues | Geographic concentration risk | South America |  |  |  |  |
Concentration percentage |  |  | 81.70% |  |
Minimum |  |  |  |  |
Number of geographical areas of operation to minimize risks |  |  | 1 |  |
Contract Drilling: | Operating revenues | Geographic concentration risk | International locations |  |  |  |  |
Concentration percentage |  |  | 14.10% |  |

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