Commitments and Contingent Liabilities - Additional Information (Detail) (USD $)	3 Months Ended
	Sep. 30, 2008	Jun. 30, 2011	Mar. 31, 2011	Sep. 15, 2008	Sep. 30, 2003
Commitments and Contingencies Disclosure [Line Items]
Number of individual claims brought against UNM					95
Loss Contingency, Loss in Period	$ 850
Miscellaneous matters, penalty each case				$ 11,000
States involved in unclaimed property examination			27
Insurers requested to cross-check benefits		160
Pending Litigation, Set for Trial
Commitments and Contingencies Disclosure [Line Items]
Number of cases decided					7
Case Decided in Favor of Plaintiff
Commitments and Contingencies Disclosure [Line Items]
Number of cases decided					2
Cases Decided in Favor of Company
Commitments and Contingencies Disclosure [Line Items]
Number of cases decided					4