Contingencies and Other Matters (Details) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2009	Dec. 31, 2011
Contingencies And Other Matters Details [Abstract]
Guaranteed Separate Accounts Liability	$ 1,700,000,000
Separate Accounts Liability Sold Business Percent Reinsured	73.00%
Underlying mutual fund investment values for Guaranteed Minimum Income Benefits	1,100,000,000
Maximum potential undiscounted payments under Guaranteed Minimum Income Benefits assumptions	1,100,000,000
Percentage of Guaranteed Minimum Income Benefit assets reinsured externally	55.00%			55.00%
Indemnification Obligations To Lenders	291,000,000
Liabilities Required Indemnification Obligations Real Estate Joint Ventures	0
Leased equipment value deficiency guarantees	44,000,000
Guarantee For Lease Shortfall Expiring 2013	28,000,000
Guarantee For Lease Shortfall Expiring 2017	16,000,000
Guarantee Liability For Lease Shortfall	17,000,000
Guarantees to banks to settle claim checks processed by the company for administrative service only customers	380,000,000
Liabilities Required Bank Service Guarantees	0
Charges for administrative service only bank guarantees	0	0
Percent reduction in exposure of guarantees to banks since balance sheet date	89.00%
Percentage of Administrative Service Only fees at risk for performance guarantees	15.00%
Percentage of ASO fees reimbursed for performance guarantees	1
Liabilities Required Indemnification Obligations Acquisitions and Dispositions	0
Estimated Potential Guaranty Fund Assessments Range	60,000,000
Charges Related to Guaranty Fund Assessments	not material
Litigation reserves pre tax	102,000,000
Litigation reserves after tax	66,000,000
Contribution to establishment of non-profit resulting from Ingenix			$ 10,000,000