Borrowings - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Sep. 30, 2017	Jul. 30, 2016
Debt Instrument [Line Items]
Unamortized debt premium, net	$ 2,833	$ 3,413
Unamortized debt issuance costs	(15,170)	(14,800)
Total debt, net	1,326,503	1,327,412
Senior Notes
Debt Instrument [Line Items]
Unamortized debt premium, net	2,833	3,413
Unamortized debt issuance costs	(15,170)	(14,800)
Total debt, net	$ 1,258,890	$ 1,259,840
Senior Notes \| 5 3/4% Senior Notes Maturing June 2019
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	5.75%	5.75%
Total debt, net	$ 96,393	$ 321,393
Senior Notes \| 8 3/4% Senior Notes Maturing March 2022
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	8.75%	8.75%
Total debt, net	$ 500,000	$ 500,000
Senior Notes \| 7 1/4% Senior Notes Maturing February 2023
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	7.25%	7.25%
Total debt, net	$ 24,834	$ 199,834
Senior Notes \| 6 3/4% Senior Notes Maturing March of 2025
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	6.75%	6.75%
Total debt, net	$ 250,000	$ 250,000
Senior Notes \| 5 7/8% Senior Notes Maturing October 2027
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	5.875%	0.00%
Total debt, net	$ 400,000	$ 0
Junior Subordinated Notes
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)			7.987%
Total debt, net	63,487	61,937
Other Secured Notes payable
Debt Instrument [Line Items]
Total debt, net	$ 4,126	$ 5,635

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28567-108399

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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