XML 53 R37.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Financial Instruments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2024
Fair Value Disclosures [Abstract] |
Estimated Fair Values of Financial Instruments | The following table presents the fair values of financial instruments:
| December 31,
| 2024 |  | 2023
| (Amounts in thousands)
Assets |  |  |
Investments | $ | 6,076,370 |  |  | $ | 5,228,520 |
Notes receivable | 31,231 |  |  | 9,974 |
Liabilities |  |  |
Options sold | 213 |  |  | 1,955 |
Notes payable | 566,812 |  |  | 557,710 |

X
- Definition Estimated Fair Values of Financial Instruments [Table Text Block] + References No definition available. + Details
Name: | mcy_EstimatedFairValuesOfFinancialInstrumentsTableTextBlock
Namespace Prefix: | mcy_
Data Type: | dtr-types1:textBlockItemType
Balance Type: | na
Period Type: | duration

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