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Debt and Other Obligations Debt and Other Obligations - General (Details) - USD ($) $ in Millions | Sep. 30, 2018 | Sep. 30, 2013 | Aug. 09, 2013 | Sep. 30, 2012 | Jan. 17, 2012
--- | --- | --- | --- | --- | ---
Debt Instrument |  |  |  |  |
Interest rate |  |  |  |  | 7.10%
Debt ceiling | $ 30,000 |  |  |  |
Face Amount | 40 |  |  |  | $ 100
Holdco |  |  |  |  |
Debt Instrument |  |  |  |  |
Face Amount |  |  |  | $ 100 |
Holdco balloon payment upon maturity | $ 10 |  |  |  |
SCCG |  |  |  |  |
Debt Instrument |  |  |  |  |
Interest rate |  |  | 3.846% |  |
Face Amount |  | $ 360 | $ 360 |  |

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