XML 103 R89.htm IDEA: XBRL DOCUMENT v3.10.0.1

Share-Based Compensation (Summary of Grants) (Details) - 2015 Plan [Member] - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant year	2016
Three-year performance period ending December 31,	2018
Vesting shares, target (net of forfeited) (in shares)	75,250
Vesting shares, maximum (net of forfeited) (in shares)	141,094

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

- Definition

Restricted Stock Units Grant Year

+ References

No definition available.

+ Details

Name:	mcy_RestrictedStockUnitsGrantYear
Namespace Prefix:	mcy_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_PlanNameAxis=mcy_TwoThousandFifteenPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: