XML 43 R30.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Fair Value Measurement (Narrative) (Details) | 9 Months Ended
--- | ---
Sep. 30, 2016 transfers broker | Sep. 30, 2015 transfers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Percentage of portfolio of unadjusted fair values obtained | 99.70% |
Percentage of portfolio of specific unadjusted broker quotes obtained | 0.30% |
Transfers between Levels 1, 2, and 3 of the fair value hierarchy | transfers | 0 | 0
Minimum [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Number of knowledgeable outside security brokers consulted to determine fair value | broker | 1 |

X
- Definition The amount of the transfers of assets or liabilities into or out of Levels 1, 2, and 3. + References No definition available. + Details
Name: | mcy_FairValueTransfersBetweenLevelsOneTwoAndThreeAmount
Namespace Prefix: | mcy_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of knowledgeable outside security brokers consulted to determine fair value. + References No definition available. + Details
Name: | mcy_NumberOfKnowledgeableOutsideSecurityBrokersConsultedToDetermineFairValue
Namespace Prefix: | mcy_
Data Type: | xbrli:positiveIntegerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of specific unadjusted broker quotes obtained + References No definition available. + Details
Name: | mcy_PercentageOfSpecificUnadjustedBrokerQuotesObtained
Namespace Prefix: | mcy_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of unadjusted fair value obtained + References No definition available. + Details
Name: | mcy_PercentageOfUnadjustedFairValueObtained
Namespace Prefix: | mcy_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |