Commercial Paper, Maximum Borrowing Capacity

No definition available.

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- Definition

Number Of One-Year Extension Options

+ References

No definition available.

+ Details

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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.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

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

+ References

+ Details

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The net cash inflow or outflow for borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(1))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Short-Term Debt: (Details)	12 Months Ended
Short-Term Debt: (Details)	Dec. 31, 2020 USD ($) credit_extension	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 30, 2018 USD ($)
Short-term Debt [Line Items]
Notes payable	$ 234,040,000	$ 349,500,000
Letters of Credit Outstanding, Amount	24,730,000	30,274,000
Commercial Paper, Maximum Borrowing Capacity	750,000,000
Net (payments) borrowings of short-term debt	(115,460,000)	163,880,000	$ (25,680,000)
Commercial Paper
Short-term Debt [Line Items]
Notes payable	234,040,000	349,500,000
Letters of Credit Outstanding, Amount	$ 0	0
Debt Instrument, Term	397 days
Debt, Weighted Average Interest Rate	0.27%
Revolving Credit Facility
Short-term Debt [Line Items]
Notes payable	$ 0	0
Letters of Credit Outstanding, Amount	$ 24,730,000	$ 30,274,000
Line of Credit Facility, Current Borrowing Capacity				$ 750,000,000
Number Of One-Year Extension Options \| credit_extension	2
Debt Instrument, Term	1 year
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,000,000,000.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.175%
Debt Issuance Cost, Gross, Noncurrent	$ 6,700,000
Revolving Credit Facility \| Base Rate
Short-term Debt [Line Items]
Line of Credit Facility, Interest Rate at Period End	0.125%
Revolving Credit Facility \| Eurodollar
Short-term Debt [Line Items]
Line of Credit Facility, Interest Rate at Period End	1.125%
Revolving Credit Facility \| Letter of Credit
Short-term Debt [Line Items]
Line of Credit Facility, Interest Rate at Period End	1.125%