Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Gross rental expense	$ 199us-gaap_LeaseAndRentalExpense	$ 202us-gaap_LeaseAndRentalExpense	$ 158us-gaap_LeaseAndRentalExpense
Less: sublease revenue	(16)	(29)	(4)
Less: Rock-McGraw rent credit	(23)mhfi_RentCredit	(20)mhfi_RentCredit	(19)mhfi_RentCredit
Net rental expense	$ 160mhfi_LeaseAndRentalExpenseNet	$ 153mhfi_LeaseAndRentalExpenseNet	$ 135mhfi_LeaseAndRentalExpenseNet

The amount of revenue recognized for the period under subleasing arrangements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 55

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6584307&loc=d3e41620-112719

Name:	us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration