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Financing: Term Loan (Details) - USD ($) $ in Thousands		3 Months Ended
	Feb. 24, 2021	Mar. 31, 2021	Mar. 31, 2020
Repayments of Other Short-term Debt		$ 200,000	$ 0
Senior Unsecured Notes Due 2021
Debt Instrument, Face Amount	$ 800,000
Senior Unsecured Notes Due 2021 | Line of Credit
Debt Instrument, Term	9 months
Debt Instrument, Face Amount	$ 800,000
Debt Instrument, Basis Spread on Variable Rate	75.00%
Payment for Debt Extinguishment or Debt Prepayment Cost		0
Repayments of Other Short-term Debt		$ 200,000
Short-term Debt, Percentage Bearing Variable Interest Rate		0.86%

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

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-SubTopic 10
-Section 45
-Paragraph 15
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Amount of cash outflow for the payment of debt classified as other, maturing within one year or the operating cycle, if longer.

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- Definition

The portion of the carrying amount of short-term borrowings outstanding as of the balance sheet date, which accrues interest at a rate subject to change from time to time.

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