Reinsurance Reinsurance (Details Textual) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Reinsurance Details
Ceded Premiums Written, Accident and Health	$ 42,000,000	$ 43,000,000
Life Insurance Recoveries on Ceded Reinsurance Contracts	231,000,000	71,000,000
Ceded Premiums Written, Life	7,000,000	26,000,000
Reinsurance Effect on Claims and Benefits Incurred, Amount Ceded	12,000,000	18,000,000
Reinsurance recoverables	19,804,000,000		2,893,000,000
Mass Mutual [Member] | Retirement Plans [Member]
Reinsurance Details
Percentage of Stockholders' Equity to Credit Concentration Risk	5.00%
Fair Value of Assets Held in Trust	8,800,000,000
Reinsurance recoverables	9,200,000,000
Prudential [Member] | Individual Life [Member]
Reinsurance Details
Percentage of Stockholders' Equity to Credit Concentration Risk	29.00%
Fair Value of Assets Held in Trust	0
Reinsurance recoverables	$ 8,700,000,000