XML 20 R18.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Fair Value of Financial Instruments (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2013
Financial Instruments, Owned, at Fair Value [Abstract] |
Estimated Fair Values of Financial Instruments | The following table presents the estimated fair values of financial instruments at September 30, 2013 and December 31, 2012.
| September 30, 2013 |  | December 31, 2012
| (Amounts in thousands)
Assets |  |  |
Investments | $ | 3,126,330 |  |  | $ | 3,180,095 |
Total return swap | $ | 346 |  |  | $ | 0 |
Liabilities |  |  |
Interest rate swap | $ | 0 |  |  | $ | 103 |
Equity contracts | $ | 0 |  |  | $ | 175 |
Secured notes | $ | 140,000 |  |  | $ | 140,000 |
Unsecured note | $ | 40,000 |  |  | $ | 0 |

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

X
- Details
Name: | us-gaap_FinancialInstrumentsOwnedAtFairValueAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration