XML 79 R63.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Investments - Estimated Fair Value Of Investments (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Fixed maturity securities: |  |
Due in one year or less | $ 245,282 |
Due after one year through five years | 1,121,053 |
Due after five years through ten years | 994,491 |
Due after ten years | 2,552,552 |
Total | $ 4,913,378 | $ 4,319,336

X
- Definition Debt Securities, Trading, Fair Value, Fiscal Year Maturity + References No definition available. + Details
Name: | mcy_DebtSecuritiesTradingFairValueFiscalYearMaturityAbstract
Namespace Prefix: | mcy_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Trading securities debt maturities after ten years fair value. + References No definition available. + Details
Name: | mcy_DebtSecuritiesTradingFairValueMaturityAllocatedAndSingleMaturityDateAfterYear10
Namespace Prefix: | mcy_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Trading securities debt maturities after five through ten years fair value. + References No definition available. + Details
Name: | mcy_DebtSecuritiesTradingFairValueMaturityAllocatedAndSingleMaturityDateAfterYear5Through10
Namespace Prefix: | mcy_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Trading securities debt maturities after one through five years fair value. + References No definition available. + Details
Name: | mcy_DebtSecuritiesTradingFairValueMaturityAllocatedAndSingleMaturityDateAfterYearOneThroughFive
Namespace Prefix: | mcy_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Trading securities debt maturities within one year fair value. + References No definition available. + Details
Name: | mcy_DebtSecuritiesTradingFairValueMaturityAllocatedAndSingleMaturityDateYearOne
Namespace Prefix: | mcy_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481830/320-10-45-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483467/210-10-45-1 + Details
Name: | us-gaap_TradingSecuritiesDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant