XML 72 R64.htm IDEA: XBRL DOCUMENT v2.4.1.9
Stockholders' Equity and Earnings Per Common Share Treasury Stock Transactions (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Equity, Class of Treasury Stock    
Number of Treasury Shares Repurchased 3.2us-gaap_TreasuryStockSharesAcquired 2.9us-gaap_TreasuryStockSharesAcquired
Cost of Shares Repurchased $ 108.1us-gaap_TreasuryStockValueAcquiredCostMethod $ 100.1us-gaap_TreasuryStockValueAcquiredCostMethod
Commission Paid on Common Stock Repurchased 0.1unm_SharesRepurchasedCostCommissions  
Repurchase Program Authorized in December 2013    
Equity, Class of Treasury Stock    
Authorized Dollar Value of Treasury Share Repurchases Under Stock Repurchase Program 750.0us-gaap_StockRepurchaseProgramAuthorizedAmount1
/ us-gaap_ShareRepurchaseProgramAxis
= unm_RepurchaseProgramAuthorizedinDecember2013Member		  
Remaining Dollar Value of Treasury Share Repurchases Authorized Under Share Repurchase Program $ 321.5us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
/ us-gaap_ShareRepurchaseProgramAxis
= unm_RepurchaseProgramAuthorizedinDecember2013Member