Deferred Acquisition Costs ("DAC"), Value Of Business Acquired ("VOBA") And Other Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended							3 Months Ended					3 Months Ended
	Sep. 30, 2012 Deferred Acquisition Costs [Member] Group Disability and Life Insurance [Member] Weighted Average	Sep. 30, 2012 Deferred Acquisition Costs [Member] Individual Policies [Member] Maximum [Member]	Sep. 30, 2012 Deferred Acquisition Costs [Member] Individual Policies [Member] Minimum [Member]	Sep. 30, 2012 Deferred Acquisition Costs [Member] Individual Deferred Annuities [Member] Weighted Average	Sep. 30, 2012 Deferred Acquisition Costs [Member] Group Annuity Products [Member] Weighted Average	Sep. 30, 2012 Value of Business Acquired [Member]	Dec. 31, 2011 Value of Business Acquired [Member]	Sep. 30, 2012 Value of Business Acquired [Member] TIAA [Member]	Sep. 30, 2012 Value of Business Acquired [Member] TIAA [Member] Maximum [Member]	Sep. 30, 2012 Value of Business Acquired [Member] Minnesota Life [Member] Maximum [Member]	Sep. 30, 2012 Other Intangible Assets [Member]	Dec. 31, 2011 Other Intangible Assets [Member]	Sep. 30, 2012 Customer Lists [Member] Weighted Average
Intangible assets, useful life	2 years 6 months 0 days	25 years 0 months 0 days	20 years 0 months 0 days	30 years 0 months 0 days	10 years 0 months 0 days				20 years 0 months 0 days	30 years 0 months 0 days			7 years 7 months 6 days
Intangible assets, accumulated amortization						$ 65.0	$ 62.4				$ 35.0	$ 30.6
Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, Impairment Write-down								$ 0.8