Aggregate collateral ratio (as defined by the underlying credit agreement)

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- Definition

Debt Instrument, Face Amount, Modification

+ References

No definition available.

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- Definition

Debt Instrument, Interest Rate, Effective Period

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No definition available.

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- Definition

Debt Instrument, Percentage Outstanding after Repurchase with Equity Offerings- Percentage of original amount of debt instrument to remain outstanding after repurchase with equity offerings

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No definition available.

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- Definition

Debt Instrument, Redemption Option with Equity Offerings, Percent of Par

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No definition available.

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- Definition

Debt Instrument, Redemption Price, Percentage of Principal Amount Outstanding After Redemption

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No definition available.

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- Definition

Debt Instrument, Repurchase Price upon Change of Control, Percent of Par

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No definition available.

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- Definition

Line of Credit Facility, Allowed Increase in Borrowing Capacity

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No definition available.

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- Definition

Line of Credit Facility, Number of Lenders

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
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- Definition

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

+ References

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt discount.

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-Name Accounting Standards Codification
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-SubTopic 30
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- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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- Definition

The cash outflow for the extinguishment of long-term borrowing, with the highest claim on the assets of the entity in case of bankruptcy or liquidation, before its maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
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- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 50
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-Paragraph 4
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Balance Type:	credit
Period Type:	duration

- References

No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 10
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Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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- Definition

The carrying amount, as of the date of the latest financial statement presented, of real estate owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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- References

No definition available.

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- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Borrowings - Narrative (Details)		1 Months Ended	3 Months Ended		6 Months Ended
Borrowings - Narrative (Details)	Jul. 30, 2016	Oct. 31, 2017 USD ($)	Mar. 31, 2018 USD ($) lender	Mar. 31, 2017 USD ($)	Mar. 31, 2018 USD ($) lender	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jan. 31, 2010 USD ($)
Line of Credit Facility [Abstract]
Amount of available borrowings under the Secured Revolving Credit Facility			$ 170,300,000		$ 170,300,000		$ 145,300,000
Senior Notes [Abstract]
Loss on extinguishment of debt			0	$ 15,563,000	25,904,000	$ 15,563,000
Non-cash loss on extinguishment of debt					3,173,000	3,676,000
Secured Debt [Abstract]
Total debt, net			1,325,457,000		1,325,457,000			$ 1,327,412,000
Senior Notes
Line of Credit Facility [Abstract]
Early repayment of senior debt			34,500,000
Senior Notes [Abstract]
Non-cash loss on extinguishment of debt			3,200,000
Secured Debt [Abstract]
Total debt, net			$ 1,258,348,000		$ 1,258,348,000			1,259,840,000
Senior Notes \| 5 7/8% Unsecured Senior Notes Maturing October 2027
Line of Credit Facility [Abstract]
Debt instrument, face amount		$ 400,000,000.0
Stated interest rate on debt instrument (percent)		5.875%
Senior Notes \| 6 3/4% Senior Notes Maturing March 2025
Line of Credit Facility [Abstract]
Debt instrument, face amount				$ 250,000,000		$ 250,000,000
Stated interest rate on debt instrument (percent)				6.75%		6.75%
Repurchase price upon change of control, percent of par				101.00%		101.00%
Percentage of debt outstanding after repurchase				35.00%		35.00%
Senior Notes \| 6 3/4% Senior Notes Maturing March 2025 \| Optional Redemption Under Indenture
Line of Credit Facility [Abstract]
Percentage of debt outstanding after repurchase				65.00%		65.00%
Redemption option, percent of par				106.75%		106.75%
Senior Notes \| 5 3/4% Senior Notes Maturing June 2019
Line of Credit Facility [Abstract]
Stated interest rate on debt instrument (percent)			5.75%		5.75%
Extinguishment of debt, amount			$ 225,000,000
Secured Debt [Abstract]
Total debt, net			$ 96,393,000		$ 96,393,000			$ 321,393,000
Senior Notes \| 7 1/4% Senior Notes Maturing February 2023
Line of Credit Facility [Abstract]
Stated interest rate on debt instrument (percent)			7.25%		7.25%			7.25%
Extinguishment of debt, amount			$ 175,000,000
Secured Debt [Abstract]
Total debt, net			24,834,000		$ 24,834,000			$ 199,834,000
Senior Notes \| Debt Instrument, Redemption, Period Two \| 5 7/8% Unsecured Senior Notes Maturing October 2027
Line of Credit Facility [Abstract]
Redemption price, percentage of principal amount redeemed		35.00%
Redemption price (as a percentage)		105.875%
Redemption price, percentage of principal amount outstanding after redemption		65.00%
Repurchase price upon change of control, percent of par				101.00%		101.00%
Senior Notes \| Debt Instrument, Redemption, Period Two \| 7 1/4% Senior Notes Maturing February 2023
Line of Credit Facility [Abstract]
Redemption price (as a percentage)					103.625%
Junior Subordinated Notes
Line of Credit Facility [Abstract]
Stated interest rate on debt instrument (percent)	7.987%
Junior Subordinated Notes [Abstract]
Effective period of debt instrument interest rate	10 years
Face amount modification									$ 75,000,000
Unamortized accretion			$ 37,803,000		$ 37,803,000			38,837,000
Secured Debt [Abstract]
Weighted average fixed interest rate of debt (percent)			4.24%		4.24%
Total debt, net			$ 62,970,000		$ 62,970,000			61,937,000
Other secured notes payable
Secured Debt [Abstract]
Weighted average fixed interest rate of debt (percent)			1.56%		1.56%
Total debt, net			$ 4,139,000		$ 4,139,000			5,635,000
Revolving Credit Facility
Line of Credit Facility [Abstract]
Credit facility borrowing capacity			200,000,000.0		200,000,000.0		180,000,000.0
Inventory assets pledged as collateral			$ 800,000,000		$ 800,000,000
Number of lenders \| lender			3		3
Borrowings outstanding under facility			$ 0		$ 0			$ 0
Letters of credit secured using cash collateral			29,700,000		29,700,000		34,700,000
Revolving Credit Facility \| Maximum
Line of Credit Facility [Abstract]
Line of credit facility, allowed increase in borrowing capacity			$ 250,000,000		$ 250,000,000
Aggregate collateral ratio			4.00		4.00
Revolving Credit Facility \| Minimum
Line of Credit Facility [Abstract]
Line of credit facility, allowed increase in borrowing capacity			$ 50,000,000		$ 50,000,000
Aggregate collateral ratio			1.00		1.00
Letter of Credit, Cash Secured
Line of Credit Facility [Abstract]
Letters of credit secured using cash collateral			$ 11,000,000		$ 11,000,000		$ 10,800,000