Income Taxes (Details)	3 Months Ended
Mar. 31, 2013
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Recognition of tax benefits threshold, likeliness of realization	50.00%

Percentage of Largest Amount of Tax Benefit Realized

No definition available.

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