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Borrowings - Schedule of Long-term Debt (Details) - USD ($)	Dec. 31, 2019	Sep. 30, 2019	Jul. 30, 2016
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (12,080,000)	$ (12,470,000)
Total debt, net	1,208,062,000	1,178,309,000
Senior Notes
Debt Instrument [Line Items]
Senior Unsecured Term Loan (Term Loan)	150,000,000	150,000,000
Unamortized debt issuance costs	(12,080,000)	(12,470,000)
Total debt, net	1,111,475,000	1,111,085,000
Senior Notes \| 6 3/4% Senior Notes Maturing March of 2025
Debt Instrument [Line Items]
Total debt, net	$ 229,555,000	229,555,000
Stated interest rate on debt instrument (percent)	6.75%
Senior Notes \| 5 7/8% Senior Notes Maturing October 2027
Debt Instrument [Line Items]
Total debt, net	$ 394,000,000	394,000,000
Stated interest rate on debt instrument (percent)	5.875%
Senior Notes \| 7 1/4% Senior Notes Maturing October 2029
Debt Instrument [Line Items]
Total debt, net	$ 350,000,000	350,000,000
Stated interest rate on debt instrument (percent)	7.25%
Junior Subordinated Notes
Debt Instrument [Line Items]
Total debt, net	$ 66,587,000	66,070,000
Stated interest rate on debt instrument (percent)			7.987%
Unamortized accretion	34,186,000	34,703,000
Other Secured Notes payable
Debt Instrument [Line Items]
Total debt, net	0	1,154,000
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving Credit Facility	$ 30,000,000	$ 0
Senior Notes \| 6 3/4% Senior Notes Maturing March of 2025
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	6.75%
Senior Notes \| 5 7/8% Senior Notes Maturing October 2027
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	5.88%
Senior Notes \| 7 1/4% Senior Notes Maturing October 2029
Debt Instrument [Line Items]
Stated interest rate on debt instrument (percent)	7.25%