XML 73 R66.htm IDEA: XBRL DOCUMENT v2.4.1.9
Debt - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Debt Narrative Detail Information  
Long-term Line of Credit $ 0us-gaap_LineOfCredit
Notes Issued in 2005  
Debt Narrative Detail Information  
Interest Rate on Debt 6.85%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= unm_NotesIssuedin2005Member
Northwind Holdings LLC  
Debt Narrative Detail Information  
Debt Principal Payments $ 29.1us-gaap_DebtInstrumentPeriodicPaymentPrincipal
/ dei_LegalEntityAxis
= unm_NorthwindHoldingsLlcMember