DEBT (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 20, 2018	Sep. 30, 2018	Mar. 19, 2015
Debt
Face Amount	$ 500,000		$ 500,000
Unamortized Debt Issuance Cost	(9,195)		(6,032)
Unamortized Debt Issuance Cost, due after one year	(9,195)		(6,032)
Long-term debt	490,805		493,968
Long-term debt	490,805		493,968
HPIDC 2025 Notes
Debt
Face Amount	500,000		500,000	$ 500,000
Unamortized Debt Issuance Cost	(9,195)		(6,032)
Long-term debt	$ 490,805	$ 12,900	$ 493,968

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

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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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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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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