Document and Entity Information (USD $) In Billions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Feb. 22, 2012	Jun. 30, 2011
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Trading Symbol	UNM
Entity Registrant Name	Unum Group
Entity Central Index Key	0000005513
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		285,849,395
Entity Public Float			$ 7.7