Fair Value Measurements - Fair Value of Other Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair value disclosures
Long-term debt	$ 1,161,712	$ 1,220,025
Current maturities	(188,000)	(87,000)
Long-term debt, excluding current maturities	973,712	1,133,025
Carrying Amount
Fair value disclosures
Long-term debt	1,161,712	1,220,025
Current maturities	(188,000)	(87,000)
Long-term debt, excluding current maturities	973,712	1,133,025
Estimated Fair Value
Fair value disclosures
Long-term debt	1,213,402	1,260,259
Current maturities	(189,501)	(88,704)
Long-term debt, excluding current maturities	$ 1,023,901	$ 1,171,555

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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 current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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