XML 97 R83.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Profit Sharing Plan and Annual Cash Bonuses (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Deferred Compensation Arrangements [Abstract] |  |  |
Maximum percentage of compensation employee is allowed to contribute | 15.00% |  |
Matching contributions | $ 9,000,000 | $ 8,600,000 | $ 8,200,000
Bonus expense, cash | $ 0 | $ 0 | $ 16,800,000

X
- Definition Individual Employees, Bonus Expense, Cash + References No definition available. + Details
Name: | mcy_IndividualEmployeesBonusExpenseCash
Namespace Prefix: | mcy_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Maximum percentage of compensation employee is allowed to contribute to the Plan. + References No definition available. + Details
Name: | mcy_MaximumPercentageOfCompensationEmployeeIsAllowedToContribute
Namespace Prefix: | mcy_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of contributions made by employer into fund established for purposes of making future disbursement to individual in accordance with deferred compensation arrangement. + References No definition available. + Details
Name: | us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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