Long-Term Debt - Current Classification of Notes (Details) - Convertible Notes Payable	3 Months Ended
Dec. 31, 2018 USD ($) trading_day $ / shares	Sep. 30, 2018 USD ($)
7.875% Convertible Notes Due 2026
Debt Instrument [Line Items]
Interest rate	7.875%
Trading days \| trading_day	20
Consecutive trading days \| trading_day	30
Conversion price threshold percentage	120.00%
Principle amount of debt \| $		$ 23,000,000
Permanent equity reclassified as mezzanine equity \| $	$ 1,000,000	$ 1,000,000
7.875% Convertible Notes Due 2026 \| Redemption Period One
Debt Instrument [Line Items]
Conversion ratio of common stock per principal	83.3333
Conversion price (in usd per share) \| $ / shares	$ 12.00
4.0% convertible notes due 2027
Debt Instrument [Line Items]
Interest rate	4.00%
Redemption price	100.00%

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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The price per share of the conversion feature embedded in the debt instrument.

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Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

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Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

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Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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