Document and Entity Information (USD $)	12 Months Ended
	Jun. 30, 2012
Document And Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Jun. 30, 2012
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2012
Current Fiscal Year End Date	--06-30
Entity Central Index Key	0001470215
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Registrant Name	Towers Watson & Co.
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Statement [Line Items]
Entity Public Float	$ 4,285,619,012
Common Class A [Member]
Statement [Line Items]
Entity Common Stock, Shares Outstanding	58,787,228
Common Class Restricted A [Member]
Statement [Line Items]
Entity Common Stock, Shares Outstanding	1,688,736
Common Class B-3 [Member]
Statement [Line Items]
Entity Common Stock, Shares Outstanding	5,661,591
Common Class B-4 [Member]
Statement [Line Items]
Entity Common Stock, Shares Outstanding	5,374,287