Long-Term Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Senior revolving credit facility maturing in 2026, net of debt issuance costs	$ 319,424	$ 212,231
Total	612,742	307,157
Amounts due within one year	20,000	20,000
Long-term debt, net of debt issuance costs	$ 592,742	287,157
2010 Senior Notes payable through 2021, 4.00%
Debt Instrument [Line Items]
Debt instrument, stated interest rate percentage	4.00%
Senior notes payable	$ 20,000	20,000
2016 Senior Notes payable through 2031, 3.40%, net of debt issuance costs
Debt Instrument [Line Items]
Debt instrument, stated interest rate percentage	3.40%
Senior notes payable	$ 73,906	74,926
2021 Senior Notes payable through 2036, 2.69%, net of debt issuance costs
Debt Instrument [Line Items]
Debt instrument, stated interest rate percentage	2.69%
Senior notes payable	$ 99,706	0
2021 Senior Notes payable through 2036, 2.69%, net of debt issuance costs
Debt Instrument [Line Items]
Debt instrument, stated interest rate percentage	2.69%
Senior notes payable	$ 99,706	$ 0

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

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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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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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-Section 50
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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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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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Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

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