XML 43 R52.htm IDEA: XBRL DOCUMENT v2.4.1.9

Investments (Estimated Fair Value Of Investments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Fixed maturity securities:
Due in one year or less	$ 42,637mcy_TradingSecuritiesDebtMaturitiesWithinOneYearFairValue
Due after one year through five years	355,106mcy_TradingSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue
Due after five years through ten years	593,934mcy_TradingSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue
Due after ten years	1,626,723mcy_TradingSecuritiesDebtMaturitiesAfterTenYearsFairValue
Total	$ 2,618,400us-gaap_InvestmentsFairValueDisclosure
Percentage of fixed maturities	1.40%mcy_PercentageOfFixedMaturitySecurities

X

- Definition

Percentage of fixed maturities rated below investment grade and non-rated.

+ References

No definition available.

+ Details

Name:	mcy_PercentageOfFixedMaturitySecurities
Namespace Prefix:	mcy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Trading securities debt maturities after five through ten years fair value.

+ References

No definition available.

+ Details

Name:	mcy_TradingSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue
Namespace Prefix:	mcy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Trading securities debt maturities after one through five years fair value.

+ References

No definition available.

+ Details

Name:	mcy_TradingSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue
Namespace Prefix:	mcy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Trading securities debt maturities after ten years fair value.

+ References

No definition available.

+ Details

Name:	mcy_TradingSecuritiesDebtMaturitiesAfterTenYearsFairValue
Namespace Prefix:	mcy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Trading securities debt maturities within one year fair value.

+ References

No definition available.

+ Details

Name:	mcy_TradingSecuritiesDebtMaturitiesWithinOneYearFairValue
Namespace Prefix:	mcy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

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