XML 105 R91.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Share-Based Compensation (Summary of Grants) (Details) - shares | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |  |
Three-year performance period ending December 31, | 2018 | 2017
Vesting shares, target (net of forfeited) | 83,250 | 85,750
Vesting shares, maximum (net of forfeited) | 156,094 | 160,781

X
- Definition Performance vesting restricted stock units, three-year performance period ending, years. + References No definition available. + Details
Name: | mcy_PerformanceVestingRestrictedStockUnitsThreeYearPerformancePeriodEndingYears
Namespace Prefix: | mcy_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Performance vesting restricted stock units, vesting shares, maximum. + References No definition available. + Details
Name: | mcy_PerformanceVestingRestrictedStockUnitsVestingSharesMaximum
Namespace Prefix: | mcy_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration