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Debt - Narrative (Details) | 3 Months Ended
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Mar. 31, 2018 $ / shares
9% Debentures |
Debt Instrument [Line Items] |
Conversion rate (in shares per $1,000 note) | 0.0740741
Convertible debt, conversion price (in dollars per share) | $ 13.50
Period preceding election to convert (in days) | 5 days
Stated interest rate | 9.00%
Senior Notes | 5.75% Senior Notes Due 2023 |
Debt Instrument [Line Items] |
Stated interest rate | 5.75%

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