XML 59 R48.htm IDEA: XBRL DOCUMENT
v3.23.3

Marketable Securities (Schedule of Amortized Cost Basis and Fair Value of Available-for-Sale Marketable Securities) (Details) $ in Millions | Sep. 30, 2023 USD ($)
--- | ---
Amortized Cost |
Less than 1 year | $ 15.8
1 to 2 years | 0.0
Amortized Cost | 15.8
Fair Value |
Less than 1 year | 15.8
1 to 2 years | 0.0
Fair Value | $ 15.8

X
- Definition Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year Two + References No definition available. + Details
Name: | musa_DebtSecuritiesAvailableForSaleAmortizedCostMaturityAllocatedAndSingleMaturityDateYearTwo
Namespace Prefix: | musa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities, Available-for-Sale Excluding Cash And Cash Equivalents + References No definition available. + Details
Name: | musa_DebtSecuritiesAvailableForSaleExcludingCashAndCashEquivalents
Namespace Prefix: | musa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities, Available-for-Sale Excluding Cash And Cash Equivalents, Amortized Cost + References No definition available. + Details
Name: | musa_DebtSecuritiesAvailableForSaleExcludingCashAndCashEquivalentsAmortizedCost
Namespace Prefix: | musa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year Two + References No definition available. + Details
Name: | musa_DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateYearTwo
Namespace Prefix: | musa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 320 -Name Accounting Standards Codification -Section 50 -Paragraph 3A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480832/942-320-50-3A + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant