Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt - Summary of Maturities (Details) - USD ($)	Dec. 31, 2021	Sep. 30, 2021	Mar. 31, 2017	Mar. 13, 2017	Dec. 31, 2015	Dec. 07, 2015
Debt Instrument [Line Items]
2022	$ 389,392,000
2023	0
2024	0
2025	0
2026	0
Thereafter	500,000,000
Total before unamortized discount	889,392,000
Less: unamortized discount and issuance costs	(45,538,000)
Total debt	843,854,000	$ 867,924,000
Convertible Debentures 1.25% Due 2025
Debt Instrument [Line Items]
Total before unamortized discount	$ 261,400,000
Stated percentage	1.25%		1.25%	1.25%
Convertible Debentures 1.0% Due 2035
Debt Instrument [Line Items]
Total before unamortized discount	$ 128,000,000
Stated percentage	1.00%				1.00%	1.00%
Convertible Debentures
Debt Instrument [Line Items]
2022	$ 389,392,000
2023	0
2024	0
2025	0
2026	0
Thereafter	0
Total before unamortized discount	389,392,000
Less: unamortized discount and issuance costs	(40,723,000)
Total debt	348,669,000
Senior Notes
Debt Instrument [Line Items]
2022
2023	0
2024	0
2025	0
2026	0
Thereafter	500,000,000
Total before unamortized discount	500,000,000
Less: unamortized discount and issuance costs	(4,815,000)
Total debt	$ 495,185,000